Jay Fisher - World Class Knifemaker

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"Random Access Three" obverse side view in CPM154CM powder metal technology high molybdenum stainless steel blade, vertical and horizontal sheaths in hand-stamped brown basketweave leather shoulder
"Random Access III"

440C: A Love/Hate Affair

"Aeolus" in 440C high chromium stainless steel cross-blade, hand-engraved 304 stainless steel bolsters, Labradorite gemstone handle, stand of peach, American black walnut, 304 stainless steel, Baltic brown granite, engraved brass
"Aeolus" is a study in 440C hollow grinds on a cross blade.

"Procyon" reverse side view in hand-engraved 440C high chromium stainless steel blade, hand-engraved 304 stainless steel bolsters, anodized 6AL4V titanium liners and lock, polished Brazilian Agate gemstone handle, breccia marble case
Hand-engraved 440C stainless steel blade in this Procyon

This Page

I first wrote this page to make clear sense to my clients, knife enthusiasts, and my knifemaking community at large the importance, use, and application of one particular type of steel we call 440C. The page has become so referenced, so popular that it is now one of the most studied and referenced pages on my website. This shows how interested people are about this particular steel alloy, and rightly so.

Welcome to my page about 440C; I'm sure you will learn more about this steel on this page than on any other knifemaker's site, knife forum or bulletin board, or discussion page... anywhere. Thanks for being here, and thanks for helping spread education in our field!

A true counterterrorism knife with 440C stainless steel blade:
"Kairos" combat, counterterrorism knife in 440C high chromium stainless steel blade, 304 stainless steel bolsters, G10 fiberglass/epoxy composite handle, hybrid tension-locking sheath in kydex, anodized aluminum, stainless steel with HULA, LIMA, and UBLX
More about the "Kairos"

What is 440C?

A martensitic stainless steel. It's composed of these major alloy elements (I don't list the minor elements since they don't play a major role) :

  • Carbon: 1.00-1.25% This increases hardenability and wear resistance, but decreases toughness in higher amounts.
  • Manganese: .45% This is added to reduce brittleness and improve forgeability, hardenability, and reducing deformation.
  • Silicon: .30% This is a deoxidizer and improves hot-forming properties.
  • Chromium: 17.00-18.00% Added in high amounts only to high alloy tool steels: this improves hardenability, high wear resistance, toughness, and corrosion resistance.
  • Molybdenum: .50% Improves deep hardening and toughness, along with wear resistance.

These basic elements (along with iron) are a simple combination that works well together, and has for many decades.

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"PJLT" USAF Pararescue CSAR custom knife, obverse side view: 440C high chromium stainless steel blade, 304 stainless steel boslters, canvas micarta phenolic handle, locking kydex, aluminum, stainless steel sheath
The distinctive toughness, corrosion resistance, and hardness of 440C in this USAF Pararescue CSAR knife.

440C: A Love/Hate Affair

This page is about a certain type of steel. Why would I choose to write about this one particular steel, to dedicate a single page to this one particular high alloy set? It's because in no other steel type have so many been misinformed, misguided, and maligned for no other reason than wives' tales, misperception, and ignorance. This happens not in industry, among engineers, machinists, or metallurgists, but among knifemakers themselves, and to a lesser degree, knife clients, owners, and enthusiasts. These are guys who should know the difference in steel types used for knife blades, their advantages and disadvantages, their pros and cons, their benefits and limitations. Unfortunately, many modern knife makers know next to nothing about this ubiquitous steel type, and yet continue to deride, decry, and attempt to deny its use as a premium knife tool steel.

This alloy is technically classified as UNS (Unified Numbering System) S44004. It's also classified as SAE (Society for Automotive Engineers) as 51440C. The American Iron and Steel Institute classifies it as 440C martensitic standard stainless steel. In European systems, it's specified as X105CrMo17. In Japan, it's SUS 440C. The Aerospace Materials Specification lists it as 5880, a "premium aircraft quality product." Most modern knifemakers simply call it 440C.

It's important to understand the background of this special type of steel. Stainless steels were invented roughly around the beginning of the 20th century. Many different alloys were experimented with, and it didn't take long to discover that chromium, the hardest of all known metals on the Periodic Table of Elements, was highly beneficial as an alloy element to steel. It was discovered that the addition of this extremely corrosion resistant, hard, brittle, and lustrous metal would make steel (basically iron with a tiny amount of carbon) a lot harder, a lot more corrosion resistant, and stronger overall. Another curious fact surfaced too, that the higher the carbon content in the chromium steel, the less corrosion resistant the stainless steel becomes. More carbon makes the steels more hardenable, and thus more wear resistant, but decreases the corrosion resistance. The issue is one of balance, a term frequently referred to in machinists' and engineers' references. This balance depends on the use, exposure, strength, and corrosion resistance needed for particular applications.

To understand this balance between carbon and chromium, here's a simplified comparison:

Wear Resistance and Corrosion Resistance in Chromium Steels
Alloy Amount Alloy Content Beneficial Effect Limitation
⇑ Carbon High Carbon, Low Chromium Higher wear resistance Lower corrosion resistance
Balance Chromium and Carbon in balance Balanced for particular use Good combination of wear resistance and corrosion resistance
⇑ Chromium High Chromium, Low Carbon Higher corrosion resistance Lower wear resistance

From this, you can see that the goal is to achieve a balance of chromium and carbon suited to the particular application. Since NO steel has been made specifically for hand knives (no matter what you may read on the internet), steels are alloyed for other similar tool and device uses. For instance, 440C is used primarily in corrosion resistant aerospace ball bearing races and balls, in nozzles, balls and seats for oil well pumps, and high wear valve parts. Engineers and machinists wouldn't use this steel if it did not perform extremely well; 440C is a durable, wear resistant, tough, and highly corrosion resistant stainless steel.

This is why it's so humorous to read on knife maker's web sites and particularly on anonymous knife forums about 440C. I'm sure that metallurgists, machinists, and engineers who are familiar with high alloy stainless and tool steels roll their eyes when anonymous knife "experts" claim that this high alloy steel is somehow inferior to a plain carbon steel. Don't laugh, this happens all the time, so much so that it's known well among experienced professionals as a novice and ignorant viewpoint. High alloy and stainless steels are superior in every conceivable way to low alloy, low carbon steels and standard steels apart from two:

  1. 440C costs more than plain carbon steels and standard steels.
  2. 440C can not be worked in an open air forge or furnace without destroying it.

 You wouldn't build a skyscraper from 440C, not because it wouldn't support the structure, but because no one could afford it! In cheap knives, they are cheap for a reason. You also can not work 440C in a plastic range for these reasons:

  1. An open air forge or furnace can not achieve and maintain the heat necessary to forge this steel in a constant plastic range.
  2. Extensive decarburization will occur if 440C is left in any open, oxygen-containing atmosphere. Decarburization is the number one reason for bad heat treating results.
  3. Stresses created in hand-forging 440C are destructive and permanent. 440C is not a forgiving steel that can be worked and reworked in a forge, hammered, cooled, heated, hammered, cooled, heated repeatedly without substantial damage to the structure and allotropes desired.
  4. 440C is not a steel to hand-forge. This is the main reason that knifemakers who hand forge do not use 440C; it's the wrong steel for that application.

Here are some salient points to ponder, particularly if you're one of those people that think that plain carbon steels are superior in performance to 440C. This typically comes up because some anonymous poster on a knife forum incorrectly claims the superiority of plain carbon or standard steels.

  • 440C is a high alloy steel with substantial amounts of alloying elements; plain carbon steels do not have a substantial amount of alloying elements.
  • 440C is a hypereutectoid steel, having much more carbon than the .8% that classifies steels as simply "eutectoid." Most carbon steels are hypoeutectoid, and though few have more than .8% carbon, none have more than the 1.0% or the 1.20% of carbon 440C has. NONE. Carbon is the major element that plays the most important role in steel's hardness, toughness, and wear resistance.
  • 440C is high in chromium. Chromium is included in this alloy for a variety of reasons:
    • it is a harder element, the hardest metal on the periodic table of elements
    • it improves hardenability overall
    • it improves toughness overall
    • it imparts substantial corrosion resistance to steel, more than any other alloy element
    • its presence increases chromium carbides and eta carbides, substantial and important molecular and crystalline structures that dramatically increase wear resistance, toughness, and durability, when properly cryogenically processed
  • Chromium has detrimental effects on steel. Here are the issues:
    • Chromium raises the hardening temperature. This is one of the reasons that a open air forge can not be used to effectively forge 440C, or any other steel that is high in chromium.
    • Because of the high hardening temperature, chromium can contribute to hardening deformation. This is another reason that 440C can not and should not be hand-forged. This also makes 440C more difficult to heat treat.
    • Chromium is resistant to machining, grinding, and finishing in particular, and this is why a lot of knifemakers do not like to work with it.
  • 440C requires a very specific, controlled, and accurate environment to process properly, and this is out of the scope of most knifemaking shops, particularly if the maker is hand-forging.
  • 440C requires a very cold process, cryogenic, in order to be brought to its highest toughness, hardness, wear resistance, corrosion resistance, and performance condition. This is out of the scope of most hand-making knife shops.

From these points, you can see that the advantages of this particular alloy are not commonly available to the guy who hand-forges blades. If he tries to hand-forge 440C, it's ruined steel. This is one of the reasons that many in the hand-forging crowd do not like this steel. It's beyond their scope, it's beyond their price range, it's beyond their finishing ability. They don't like it, and are quick to claim that everyone else should dislike it, too.

I know that professional metallurgists, engineers, and machinists who work with a variety of steels and their associated processes snicker at the guys who make boastful claims about plain carbon steels and standard steels. It's hard to take knifemaking seriously unless knifemakers are more serious about the steels, processes, logic, and scientific reasoning behind their steel choices and use.

For decades, I have tried to promote professionalism in our tradecraft, science, and art. My only hope is that the seeds I plant here take root in the minds of knife enthusiasts and makers, and they realize that there is a place for all steels, advantages and limitations to every one, whether it's economic, performance-based, appearance-based, or process-based.

For more information, link to my Heat Treating and Cryogenic Treatment of Knife Blades page.

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"Freedom's Promise" obverse side view in hand-engraved 440C high chromium stainless steel blade, blued steel guard and pommel, ivory, opals, sodalite, jasper, quartz, crocidolite handle, hand-carved leather sheath with gold wash
Hand-engraved and mirror polished 440C on this Freedom's Promise

440, 440A, 440B, and 440C

I've seen these designations as a source of confusion in the knifemaking field for decades, and it's time to set some things straight. First, there is no "440" stainless steel. Without the letter designation, it's like claiming your car is a 20th century version (not identifying the year or the model)! Yes, I drive a 1900's car; it's a great car; it was built in the 1900s. How ridiculous is that? Yet I've seen this again and again in not only individual knife maker's sites, but in knife manufacturer's advertisements as well. The numbers 440 without the A, B, or C designation after them are essentially meaningless. Just Google the term 440 steel and see the endless list of makers and manufacturers that are proud to spew their ignorance about this type of steel, calling it surgical stainless, dive stainless, or other terms that demonstrate their lack of knowledge about the term they are attempting to define.

440A: this is a hardenable stainless steel alloy, hardenable to a higher hardness than 420 series stainless steels (which are only hardenable to 52 HRC). 440A has good corrosion resistance, and is used in less expensive bearings and in harder surgical tools (rare). It has 0.6 to 0.75 percent carbon, about the same carbon content as most steel springs. Its advantage is that is cheaper than 440B and slightly more corrosion resistant.

440B: this is a hardenable stainless steel alloy, hardenable to a higher hardness than 440A. It has good corrosion resistance and is used in cutlery (economy), valves, and instrument bearings, where high wear is less important than high corrosion resistance. It has 0.75 to 0.95 percent carbon.

440C: this is also a hardenable stainless steel alloy, hardenable to a higher hardness than 440B. It has good corrosion resistance, and is used in ball bearing balls and races, high pressure nozzles, valve seats and high wear components. It has 0.95 to 1.20 percent carbon. As detailed in the Machinery's Handbook: "This steel has the greatest quenched hardness and wear resistance upon heat treatment of any corrosion-resistant or heat-resistant steel."

All three of these steels have the same amount of chromium, from 16 to 18 percent. They are all high chromium martensitic standard stainless steels. All of their other alloy elements are about the same, including manganese, silicon, phosphorus, sulfur, and molybdenum. Clearly, the difference in these three is the carbon content, which is substantial. The higher carbon content in 440C yields a much more wear resistant knife blade. More about carbon on my "Heat Treating and Cryogenic Processing of Knife Blade Steels" page.

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"Andrimne" Chef's Master Knife, obverse side view in 440C high chromium stainless steel blade, 304 stainless steel guard ferrule and pommel ferrule, Peach hardwood turned handle, hand-stamped, hand-laced leather sheath
Elegant, tough, and beautiful mirror polished 440C on this professional restaurant chef's knife, "Andrimne"

440C Has distinctive and unique advantages

440C has some very distinctive and unique advantages. If it did not, there would not be a place for it in the realm of high alloy tool steels, it would not be produced, and it would not occupy the position of one of the most used, depended on, and proven steels in many industries. It occupies this position because it's a proven performer, and has some unique properties that other steels don't have in the exact configuration.

  • Corrosion Resistance: This is the most seldom referred to, but outstanding properties of 440C, a characteristic that few anonymous forum posters, data sheet experts, or factory knife aficionados even mention. They don't mention it (or seldom mention it) because they are usually in a race to see which one can show that he knows more about steels than the next unqualified commenter. The fact that is most often ignored by these types, and what is important for the knife client, knife owner, and knife user to know is that there are very few steels that can exceed 440C in corrosion resistance, particularly when 440C is properly cryogenically hardened, tempered, and polished. Some armchair experts and novice knifemakers will even claim that ATS-34, CPM 154CM, S30V, and CTS-XHP are more corrosion resistant, but this is not true. All of these listed steels have lower corrosion resistance than 440C, and this is why 440C is often chosen over those steels. CPMS30V (and CPMS90V and CPMS35VN) can not even be mirror polished, but even in a blasted, flat, or sanded finish, they are not as corrosion resistant as 440C. When my clients request a steel that is a "high" stainless steel, that is, they want it to resist corrosion to a greater degree than other hypereutectoid high alloy stainless steels, 440C is the leader. Nitrogen steels like N360 will resist corrosion to a greater degree, but they are not as wear resistant, and they are not available in sizes needed for serious, heavy duty use knives, and they are not proven in decades and decades of use. High wear resistance, high toughness, at very high corrosion resistance are the reasons that most of my clients request 440C. They don't want to be babying their blades, worrying about a drop of water, drying, waxing, oiling them lest they start to rust, corrode, and pit. Uses that most clients request for 440C are working knives, chef's knives, tactical knives in marine environments, counterterrorism knives in marine and wet environments, and collector's knives. In a collector's or investment grade knife, 440C requires little or no care, simply being left dry assures it will maintain it's pristine finish indefinitely. While there is no steel that will not corrode in any exposure (think acids, caustics, and salts), 440C is at the top of the list.
  • High wear resistance: This one is important, as wear resistance is a key factor in modern tool steels. Steels like D2, CPMS30V, CPMS90V and CTS-XHP all can excel in wear resistance above 440C, but they have their limitations, mainly corrosion resistance and toughness, which can both be lower than 440C. When cherry picking argument points against 440C, and in factory data sheets, wear resistance is often thrown out there, because it is important. But understand that the relative wear resistance of all of these steels is only slightly detectable in most knife use! If you were given a knife of 440C and it was identical to CTS-XHP, you would be hard-pressed to be able to determine the difference in the two steels simply by using them. This is because most knife users aren't exposed to any high alloy steels, and both would seem to cut tremendously well! I only compare CTS-XHP because the other three steels I mentioned can not achieve a bright, mirror finish, and would not be as corrosion resistant. That is because CTS-XHP has less chromium, and more carbon than 440C.
  • High toughness: Another important point, though this is critical on levels only applicable in severe use blades that are subject to impact, have tremendously thin edges, and have blades that are expected to flex. In most knives (at least the kind that my clients request) toughness is a secondary factor, giving preference to high wear resistance and high corrosion resistance first. There are tougher steels, and it's hard to beat ATS-34, CPMS35VN, and CPM 154CM. Only ATS-34 and CPM 154CM can be mirror polished, and they are both tougher than 440C when properly hardened, tempered, and polished. However, both of these steels are less corrosion resistant, and there is a significant difference in their ability to resist corrosion as much as 440C. So significant is this that my counterterrorism clients who mostly request ATS-34 do not want ATS-34 if they are in marine environments. By the way ATS-34 and CPM154CM are very similar alloys, only CPM is Crucible Particle Metallurgy (CPM) tool steel, a powder metal alloy made in high purity environments. Again, corrosion resistance plays a large factor, as it is reduced in these tougher steels.
  • Molybdenum: rarely mentioned in the make-up of 440C is the presence of 0.5% of molybdenum. Molybdenum improves hardenability, toughness, creep resistance, strength, corrosion resistance, and abrasion resistance. The inclusion of molybdenum creates nucleation initialization sites for the growth of molybdenum carbides and eta carbides, and helps carbide formation particularly with cryogenic processing and aging. Though the amount in 440C is eclipsed by the amount in ATS-34 and CPM154CM, it is substantial in 440C and contributes greatly to the overall performance of this steel. Rarely is molybdenum mentioned in discussions of 440C, but it contains more molybdenum than all carbon steels, 5160 steel, 420 stainless steel, AEB-L,15N20, 13C26, 14C28N, 19C27, and O1—none of these steels contain any molybdenum.
  • Cost: This is an often repeated factor in discussions about the use of 440C steel in knife blades, and novices, hobbyists, and armchair metallurgists that claim to know knife blade steels typically lean on this as the reason to ignore 440C. They claim it is a cheap steel, therefore, not as good. This is typical of the ignorance of the quick scan of the web, the shallow and ridiculous statements on forums, and the laziness of the guys who don't want to be bothered to actually read any informative evaluations. They are in a hurry to post their own opinion, or they are in a hurry to get just a bit of information they consider relevant to their immediate needs, and it's truly sad. I may sound like a grumpy old man, but really, it's easy to see most of the younger men in a big hurry to just get enough information to get by, and not actually study, train, and participate in the field. This is a sad commentary on our instantaneous gratification, high technology, low information-high volume, data-driven society, and it does our tradecraft no good.
    But back to the cost. The cost of a knife blade bears little on the steel used in its production in singular works; the steel cost is significant only when huge volume sales are considered. So, in factory knives, where hundreds or perhaps thousands of pounds of steel are moving into the production facility, cost does play a large role. This is why most manufactured knives nowadays are made of 420 stainless steel, the bottom-feeder of stainless steels. Following this are razor blade steels (AEB-L, 13C26, 14C28N) and next box cutter steels (19C27). In the handmade knife world, the cost of the blade steel plays a very small role in the choice of the project. How can I say this? Here's how to make this simple to understand: In a large fine collector's knife, the blade steel initial cost is in the range of 3% to 6% of the actual cost of the knife. The difference in steel choice based on actual steel cost means the difference of about 3% in choice. Choose a less expensive steel: pay 3% of the total knife value, choose a more expensive steel and pay 6%. Can you see how this argument does not apply to fine handmade knives? When these great intellects are blaming steel cost, know that they are talking about factory knives, not fine, handmade, and custom works. But factory knives are their only area of exposure.

Notice that the main and repeated characteristic of 440C mentioned in this section is "corrosion resistance." This is a profound and significant feature of this proven martensitic, high alloy, hypereutectoid, stainless steel.

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Dear Mr. Fisher,
I was compelled to write you and thank you. I do not work with knives, but I am a craftsman building high end French horns. I return to your site often when I feel discouraged or unclear about the direction of my business and the struggle to produce meaningful work. Seeing your uncompromising commitment to quality and beauty helps me to refocus and redouble my efforts in the hopes that I may one day have a portfolio as impressive and impactful as yours. Thank you for setting a high bar and being an artistic inspiration for this craftsman.

My best,
Jacob Medlin

"Orion" obverse side view in 440C high chromium stainless steel blade, hand-engraved 304 stainless steel bolsters, Rio Grande Agate gemstone  handle, hand-carved leather sheath inlaid with frog skin
Beauty and accuracy in high chromium stainless 440C: "Orion"

What about the newer alloys?

440C has been around a while. It's not a new, exciting, or proprietary steel, it's not a gimmick, not a flash in the pan. It's been around a while strictly because it is a very good steel; it has staying power. The same thing can be said of D2, the extremely high carbon die steel, and the same can be said of O1, oil hardening tool and die steel. These (and many others) are not new steels, and thus, they are not as exciting as some of the newer alloys.

There are some interesting things about knife steel alloys that makers and manufacturers seldom talk about. It's the constant attempt to hype-sell the steel, to present some new and exciting alloy as the best, the superior, the finest, the optimum, the top quality, the most durable, the most attractive, and the most valuable. Every one of these descriptive words mean absolutely nothing about the final finished product of a hand knife, nothing at all! These are not terms defined and recorded in any engineer's handbook, in any American Iron and Steel Institute (AISI) reference, in any ASME, or ASTM, or ANSI charts or literature about steels. They are sales adjectives created to make certain knives more appealing. So when someone comes up with a new alloy, they give it a new name or number, and then throw out those tiresome adjectives in hopes of hooking a fish or two that are excited about that shiny lure of a new steel. This is advertising 101, and I hope you recognize the process. I advertise too, but I do it with reams of hard text and hundreds of photos and testimonials. Sell the fluff or sell the facts and experience.

There are new alloys all the time, and you'll see one thing in common with all of them. More details at this link. They compare their subjective performance details to one steel in particular. This one steel that is the benchmark for all comparisons of new stainless and wear-resistant alloy steels is—surprise—440C. Why do you think that is?

It's because 440C is a tried, true, and proven standard that is here to stay. It's interesting to note that no one steel has come and wiped 440C off the field, replaced every application of 440C in industry, manufacturing, or the military industrial field. 440C—that old, boring high chromium, hardenable, wear-resistant martensitic steel—is here to stay.

Are there other good alloys? Of course there are, and many of them have marked advantages over 440C! You may be surprised to hear that at the time of this writing, I use over a dozen different steels, and every one of them has certain advantages and certain (and sometimes defeating) limitations. Take the CPM steels, made by the crucible particle technology process. They are great steels, they are very expensive, and each one has its own attributes. CPM154CM is a beautiful steel, but when compared to 440C, is less corrosion resistant.

...And the low information critic's attacks begin

This last comment got some attention on one of the knife forums. One guy said that CPM154CM did not exist, and I didn't know my steels. Sigh. CPM154CM is 154 CM (you can choose to use the space or not) made by Crucible Particle Metallurgy (now Crucible Industries) by the crucible particle metallurgy process (CPM). We all know what this steel is and many companies call it this, including the company that makes it and the suppliers that sell it. It saddens me, that with all the information provided by experienced professionals, there really is no reason to be so terribly misinformed. Call up Crucible and ask for it, use it. And the corrosion resistance? I find it is a bit less corrosion resistant than 440C. Why is that? Because it has less chromium (14%) than 440C (17%). How do I know? I use both of these steels, and many others, and have used many different steels for decades, successfully. And yet somehow, according to anonymous posters, I don't know what I'm doing... This is why I make knives for some of the top counterterrorism units in the world, and some of our top military... and the complainers make...what exactly? Have they actually used these steels to make knives, or are they "Data Sheet Experts," who just read what the suppliers provide and regurgitate it? They have even accused me of sitting on a stockpile of 440C trying to sell it! What about the other 10 steel types I use? Oh, it's more convenient to argue about 440C than to look over an entire group of applications of a wide variety of tool steels with intelligence. The application of steel choice that I use is all very clearly illustrated at this bookmark, with three main characteristics and twelve different individual factors. They claim I write about 440C steel because I'm simply trying to sell my knives. True, this is JayFisher.com, where I do take custom orders and sell my knives. However, I've sold thousands of 440C-bladed knives for over three decades before I wrote this page. This page is a service to my tradecraft, industry, and knife enthusiast. And what about the other steels I write about? I'm building new pages all the time, as I use more and more different tool steels; they're not complaining about them. People like to single out 440C; this is what I mean about the "Love/Hate" affair of 440C and the uninformed and inexperienced commentary simply illustrates this. I hope that you, reading this, will consider the source of all comments about all things knife related.

On these same venues (usually forums and other knifemaker's websites), you can read comments from guys who claim that makers are "sitting on" hoards of 440C purchased years ago. The person claiming this is a fool. No knifemaker sits on hoards of any steel. Why? If the poster were actually in the business of knifemaking, and had been for years, it wouldn't take long to realize that knifemakers do not buy huge amounts of any material, because of two main reasons: they don't make huge amounts of knives and do not know what their clients will request in steels, and because (like all businesses) we are taxed on the amount of inventory (in steel as well as other material) we hold over from one year to the next. Therefore, it costs money to hold onto inventory, and no one does this. I've never heard of any knifemaker who sits on loads of material; that's a story made up years ago by a guy who doesn't know why makers choose the steels they do. These people won't ever change and learn, they simply continue on in low information, while the rest of us move forward. They croak to each other their precious opinions, based on...what, exactly?

Consider who they are, who they make for, what they have accomplished in this field, and what their longevity is. Are they actually knifemakers, or just anonymous guys who like to talk about steels? Watch how they comment as if they are trained and certified metallurgists; are they? Are they just parroting information they gleaned somewhere else? Take a very good, long, hard look at their website, their knives, their standing in the knife world. Then, make your own intelligent, weighted decision.

One final thing: I'm getting pretty tired of the uninformed on these anonymous forums claiming I don't make knives to use. I've made thousands of knives, knives that perform some of the most critical warfare, work, professional applications, and tasks there are. Go look at my Tactical Combat Knives page, just for a start. Go look at my Pararescue page. Go look at my Counterterrorism Knives page, where are illustrated and described the knives I make for the very top counterterrorism teams in the world. Take a good look; these are real knives used by some of the best military and law enforcement professionals in the world. Good grief, I'm making knives for the top counterterrorism units in the world and somehow, I don't' know what I'm talking about! I'm not the only one making this type of knife, but to make broad comments trying to slam my work by insinuating that I don't make real working knives is just a lie.

... yeah, I'm passionate about what I do.

You won't see negative comments (like lower corrosion resistance) about any steel alloys on company data sheets, only the claims of higher hardness and wear resistance and carbide content. By the way, don't always trust manufacturer's data sheets, Crucible Steel reps have told me face to face that there are "misprints" on these sheets that (surprisingly) suggest higher performance characteristics than 440C. One such misprint is claiming that CPMS35VN can be mirror polished, when it can not be mirror polished due to the high vanadium carbides that are present after heat treating. Whoops! Okay, it's just a misprint. Or how about claims that CPMS30V is more corrosion resistant than 440C, yet this steel can not be mirror polished which is a leading factor in corrosion resistance? More on that at this bookmark. So if you can't entirely trust a manufacturer's data sheet, what can you trust? Who you should be able to trust is someone who has had decades of using many steel types for many knives; they are the guys with the know-how. More on that below.

Another example of painting newer steels as superior can be found in what is not said. Many of these newer alloys have totally ignored toughness as a benefit. Toughness is the resistance to breakage or fracture, or the ability to resist molecules of the steel from tearing apart, which not only presents itself as a break, but presents on a microscopic level as cutting edge dullness! Unless you've got a 100X microscope, you're not going to be able to detail this on a knife edge. More details at this bookmark.

Am I a "proponent" of 440C?

It's funny how people express what they think they know on public forums. On one forum, some anonymous carbon steel enthusiast (carbon steel is the very worst type of steel for any modern knife blade) claimed that I was one of the last proponents of 440C. Really? Let's look that rather uninformed claim over a bit to see where the truth lies.

First, 440C in general. There is a reason that 440C is widely used in industry and machine shops all over the world. It's a great, corrosion resistant, wear resistant stainless steel. If if weren't, it simply would not be used on valve seats, shear blades, and ball bearings as well as fine knives. When a knife client wants a highly corrosion resistant, tough, and wear resistant steel (in that order) 440c is very hard to beat. When the uninformed go on and on about newer "super" steels, they would do well to educate themselves a bit about steels in general, and stainless steels in particular. Let's look at each distinctive advantage and limitation of 440c (again, sigh), to see if sense can be made of its place in modern tools.

Corrosion resistance. The main claim to fame of 440C but is it the "best?" Best is a subjective term, because there are so many other factors, but let's, for the sake of education, toss everything else aside but corrosion resistance. 440C is highly, highly corrosion resistant, particularly when properly hardened and tempered. Do you know that these stainless steels become more corrosion resistant the harder they are? Do you know that improper heat treating and variable temper in a knife affects corrosion resistance? Okay, is there a more corrosion resistant tool steel than 440C? Sure there is, and one great steel in this realm is N360, Böhlers N360 ISOEXTRA® nitrogen stainless tool steel. It has very little carbon and thus is highly corrosion resistant and you can read more about this steel I use to make counterterrorism dive knives at the Synan and Xanthid pages. But it's not as wear resistant as 440C, and it's extremely limited in sizes and is fairly expensive. It's not the expense that limits it; it's the wear resistance and the availability, and Bohler won't seem to make it in .250" thickness and wider widths.

Toughness. 440C can be made very tough, but not as tough as ATS-34. By the way, I've made hundreds of knives in ATS-34, and it's my main counterterrorism knife material. But ATS-34, very tough with its higher percentage of molybdenum, is not as corrosion resistant. So, the knife owner will have to pay higher attention to its exposure and storage than 440C. CPM154CM is a finer, powder metal version of ATS-34, but is more expensive and limited in sizes and is also not as corrosion resistant as 440C at high hardness.

Wear resistance. There are a group of steels that are more wear resistant than 440C, and some are so wear resistant that they are hard to sharpen! But, none of them are as tough or as corrosion resistant as 440C, so there is a large tradeoff. D2, CPMS30V, CPMS90V, and CTS-XHP and others all have other limitations that must be considered in their use.

Those are just three simplified considerations for this steel type comparison, and if you think it could get very confusing and complicated, you are correct. 440C has its uses; it's a great steel with a long record of successful performance. Most of my clients still ask for 440C, and they do so because they want a tough, wear resistant tool steel that they don't have to worry about rusting, pitting, discoloring, and staining at the first exposure to moisture. While I have made most of my knives in 440C, it's because my clients want it, not because I'm stuck on any particular steel or are a proponent of one particular steel. I love them all, and just like the comparison between an agate or jade handle, a G10 or Micarta® handle, a persimmon or a eucalyptus burl handle, each material has its own particular and distinctive appeal. I simply make what my clients want, and that has given me great success in this career field for decades. That's what anonymous posters on forums don't get; I work for my clients, not some anonymous carbon steel enthusiast's mistaken idealized factory production product he writes about on a public forum.

440C and haters on the forums

My name comes up often in knife and blade forum discussions about 440C. When my name is brought into the bickering (that's mostly what forums are), it's often associated with 440C like that's the only steel I use. Never mind the ten other steels I use to make custom, handmade, tactical combat, and counterterrorism knives. The haters focus on my name, on 440C, and make all kinds of ridiculous claims and insults, while they try to diminish, offend, and decry my use of this simple steel. This bears some explanation, because when one's name is brought into an argument (seldom a simple discussion), it's important to explain with education, because knowledge is lacking with many of these guys, so here are some important considerations when you read these kinds of cowardly insults and wannabe attacks, hurled from the safety of internet anonymity:

  • Who is the person making the comment? Are they knifemakers? Are they metallurgists? Are they knife owners, and if so, what knives do they own and why? Are they professional users? Are they actually knowledgeable about knives or are they swept up in pop steels, vague performance graphs, data sheet numbers, and ambiguous, unscientific comparisons? Having 16,000 posts on a forum does not make one an expert in the subject of the forum, it usually means that the person has way too much time on their hands, time that could actually be used reading, studying, and using the knowledge that they claim to profess. I can imagine that the comeback to this statement is that Jay Fisher spends a lot of time writing on his website, but understand that this is my profession and something I do know quite a lot about. Take some time, look around, understand who I make knives for and why, and look at the thousands of knives I've made in my career. I speak from experience, which is the definitive difference between what I know and write about and what a poster on a knife forum knows and writes about.
  • Why is my name associated with this one steel? This is an easy answer, and it's not because I make knives only out of this steel; it's because of this very page that you are reading right now. At the time of this writing, if you put "440C Knife Blades" into most search engines (Google is a great example), you'll find that this page is the first page recommended in the entire world. Why is that? Because this page has the most detailed, applicable, and extensive explanation and information about 440C knife blade steel in the world, that's why. So, when forum "experts" who know nothing about steels but what they can quickly scan to get back to make post number 16,001, they undoubtedly have this page pop up in their face, over and over. And then when other people mention my name and that I possibly know something about 440C used in knife blades, they are offended again! "Oh, the humiliation! That deserves another post! And I can increase my post count, hee, hee, hee... which makes me more important here on this forum."
  • What about other makers using 440C? Some of the best makers in the world have used and are using 440C, but their names are never mentioned in the posts of ignorance. The reason for this is it's easiest to attack Jay Fisher, for this very page and his use of this steel, than to actually look up other makers and their steel choices. After all, this page has popped up in their face, and other knifemakers don't bother to write dozens of pages of information about any of the steels they use, which is, of course, their prerogative. So, simply because I've bothered to take the time to educate about knifemaking on this very website, I am insulted for doing so. Other makers simply don't bother to share what they know, or do it in a limited fashion, so their names don't pop up as often. The reason I write so much about this, by the way, is that I consider it a service aspect to my business and profession, and owe it to my clients to give them as much information as possible.
  • Why do I use 440C? This one escapes all of those ignorant posters working on their post count numbers. I use this steel for the same reason I use the other ten types of steel I use: my clients ask for it! Yep, it's that simple. This fact escapes the forum geniuses who would then claim my clients are wrong, as wrong as I am, as wrong as anyone can be for choosing a steel type different than they decree! After all, they're experts, with thousands of posts... expertly posted!
  • Old and dated: this is the latest lame attack that pops up. Because I've been making knives for so long, and because I've obviously made so many knives, my work (and 440C) must be passé, last century, antiquated, and therefore undesirable. They're convinced my steel choices are dated, my website is dated, my finish, handles, sheaths are dated, etc. Here's what they don't understand: I'm in a tradecraft and art that values experience. It's not about who is the newest maker using the newest steel type; it's about who is the most experienced and knowledgeable in their field and who does the best job. It's about who has a track record of excellent work, who's work is desired because of their understanding, skill, proficiency, dedication to the craft, and proven reliability in the field. By the way, I work directly with modern clients making modern, high tech knives, and don't copy Japanese and antique or primitive styles, or use antiquated third world hand-forging techniques to hammer-weld steel, and there is no blacksmith in any machine shop in the world, anywhere! This is why I'm I can't keep but a few knives available for sale on the website. I'm grateful to and owe my deepest thanks to two groups of people only: my clients and my familiy. Clients are who I make for, and who I think of the entire time I'm building each knife and ensemble, by hand. Want to know more about my clients? Please do take some time and read several hundred testimonials they have kindly contributed. My family has been kind and supportive my entire career.
  • New and exciting: How can knives be new and exciting if the steel is an older tried and true performer? Hold on to your hat, because knives are not just about knife blade steel type! First, look at styles of the knife. Currently, I have over 450 different knife designs and patterns and I have a dozen new ones that haven't even made it to my Patterns Page yet. I have new sheath styles, new accessories, new finishes and combinations. Continually progressing is my embellishment, metal treatments, handle materials, and display and presentation. While I am an older maker, I'm continuing my development in all realms of making, and it's working extremely well, and I'm very excited about all my projects, past, present, and future.

Now, if you're one of those forum participants who might believe that I use only one type of steel, here are some links to pages and topics of other types of steel I use and my detailed explanation of why I do or don't use them. If you are in a hurry to increase your individual post count and can't be bothered to read any actual facts based on experience and knowledge in this field, I understand. After all, you're trying to get to post number 20,000 before the year is up; it's a personal commitment to validate your place in the cosmos. For the rest of you who simply want to learn, feel free to partake of what I have learned from being a knifemaker for nearly 40 successful years:

  1. Blades page topic: The steels I use, don't use, and why, includes: ATS-34, 154CM, CPM154CM, O1, O2, Plain Carbon (Standard) Steels, D2, CPMS30V, CPMS60V, CPMS90V, CTS-XHP, N360, N690, L6, CTS-40CP, AEB-L, 13C26, 14C28N, 19C27, ZDP-189, S7, CPM 3V, SM 100, and Amorphous Alloys (Bulk Metallic Glasses)
  2. O1: Oil Hardened Blued Beauty
  3. ATS-34: Chrome/Moly Tough
  4. D2: Wear Resistance King
  5. Heat Treating and Cryogenic Processing of Knife Blade Steels

There are more individual pages in the works, for some of the more dominant steels I use, so feel free to check back on the website; it's free, it's always up, and always updated. That's my post count: based in practice in the field, and dedicated to stop myths, wives' tales, and ignorance in my tradecraft.

Frankly, there simply is no ultimate steel for knife blades, no superior, magnificent, ultimate blade material. Each choice of steel for a knife blade is a decision of balance of many properties. By the way, do you want to know what people are ignoring when they go on and on about knife blade steels; what is even more important and lacking in modern knives? Try the Six Distinctions of Fine Knives.

Knife buyers are just like everybody else; they can be swayed towards a particular knife buying decision based on advertising. Who wouldn't want the newest truck, the newest tool, the newest snack, or the newest knife? How do you make a knife, a tool that has existed for longer than any other tool in the history of man sound and seem new? Sure, people need knives, they use knives, and they collect knives. What could be more appealing than the newest, most exotic, most astounding performing steel made today? Why, even I would want to buy that! One problem though: it doesn't exist. See the next topic.

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Mr. Fisher, 
Thank you for ruining me. I was blissfully happy in my ignorance. Now through your fantastically informational website I have become a little less ignorant on knives, steel and what a true custom knife should be.
Wow! You are an artist. Period. Knife, sheath, stone and photography are extremely difficult to surpass.
I found your site doing a search on Buck Knives steel. I had noticed they didn't look or perform like my old, old, old ones. 420HC vs. 440c. Reading a few forums, I immediately knew I was reading opinions and bunk, not facts. Eureka!!! 440C a love hate relationship. Now I know facts. The knowledge I have gained in a short time has really, really been more than enjoyable. The carbide molecule sharpening too funny!!! Ignorance can be cured.
      One day soon I hope to find the funds.

Thank you Sir.
Chris Williams
Red Bank, MS

United States Air Force "Paraeagle" Combat SAR knife in etched 440C high chromium stainless steel blade, 304 stainless steel bolsters, Bocote (Cordia) hardwood handle, tension kydex, aluminum, stainless steel sheath
Paraeagle designed by a top PJ, now Commander of the 342nd Training Squadron

"Duhovni Ratnik" reverse side view. Ancient Croatian Script Glagoljica hand-engraved in hollow grind.
The bold engraving and form of sculpted 440C high chromium martensitic stainless steel in this "Duhovni Ratnik"

Why do they claim their steel is superior and how can I find the truth?

There simply is no ultimate steel for knife blades, no superior, magnificent, ultimate blade material. Please understand this: If there were a superior steel or other exotic metal, all others would be cast aside, no longer made at any foundry, and they would be sentenced to the ashbin of obsolescence. Every steel has its pros and cons, its advantages and disadvantages. So advertisers need to make something sound new and better (even if it is cheaper and worse), so they claim a new steel, a better steel, a rarer steel, a superior steel is used in their product. Isn't it funny that they never claim new or superior handles, bolsters, or sheaths, only the blade steel? That's because they know that you, as a consumer, have limitations that prevent you from knowing the truth. How does this happen?

  • They know that you will not have the steel tested by a certified metallurgist to determine exactly what the steel is.
  • They know that you will not use the knife in such a way as to notice any difference in any performance from earlier steels.
  • They know that there is no real testing of knife blade steel performance, only subjective comparisons based on vague properties that are not scientifically defined.
  • They know that if you are unsatisfied, they amount you pay is either not enough for you to care about, is not too much for them to refund, or that you will be satisfied with a replacement of the same item.
  • They know that you are influenced, hoodwinked, and taken in by advertising hype consisting of unsubstantiated claims.
  • They know that there is no official, law enforcing, or sanctioned authority that will police their lies, claims, and inflated hype to make them tell the truth in their advertising.
  • They think you are too stupid, ignorant, or careless to bother to research the topics presented by proven masters and highly experienced professionals in this field, and will simply go with the herd.
  • They know you, who are reading this website, are not their customers.

Okay, so is most of what you read about knife blade performance hype? It really depends on who is presenting it, and this is very important. If you are a knife client, buyer, or user, there is a simple way to know whether your knifemaker, knife factory, and knife supplier is selling the hype or knows what he is talking about. Look at his knives!

  • Look at the website; if there isn't a substantial web presence, they are not modern or advanced makers tuned to make and respond to modern knife use, design, or appeal. Their website demonstrates their participation, or lack thereof, in the professional knifemaking field. Look for information, lots of it. There simply is no reason a knifemaker or (worse) a knife manufacturer will not take the time to offer every available piece of information about the product they sell. If I, as an individual knifemaker can do it, certainly a large corporation with dozens or hundreds of employees can too! If it's a single knifemaker you intend to buy from, know that how he "wears" his website demonstrates how he treats his clients, because this is the service aspect of our field. More on service at this bookmark.
  • Look at his testimonials. Are they realistic, are they plentiful? Do they seem like they are all made by one writer, or do the individual testimonials have their own voice?
  • Look who he makes for. This should be clearly presented, with plenty of references, testimonials, and types of knife in his particular field.
  • Look at his history. A new maker is not an experienced maker. There is no shortcut, no fast track to knifemaking skill. There is no cultural claim to fine knives (like is so often seen in Japanese style sites and products). The history of the maker should be well established and clearly defined without hype.
  • Overall and most importantly: LOOK AT THE KNIVES! Do they look finely made, are the grinds crisp and uniform, are the finishes complete and precise? Do they have an excellent and precise fit? Do they even offer large, clear, and plentiful photos that you can see the fit at all, or are they just small, dinky profile photos? Have they painted the blade? Are there three ridiculous rivets securing the handle to the tang? Is the tang tapered for balance? Are the blades ground to their purpose, are there a large variety of styles, patterns, and designs to choose from, or are they just 4" drop points or stag handled bowies? Are the handle materials wide-ranging and exotic, as well as domestic? Are there fittings on the knife (bolsters)? Are there good sheaths? Good stands, good cases? Or is the maker or manufacturer just making a simple, plain, boring knife, and then hyping the steel type in hopes you'll buy?
  • Probably most important: does the maker make real combat knives? Why do I include this? This is included because these are frequently the most durable, most well-made, most challenging, and most important endorsements of the maker's experience. I don't mean knives that are stylistically tactical, I mean real combat knives made for and used by professionals in the field of war, counterterrorism, or law enforcement. While many makers and manufacturers claim to be making these knives, their reputation, their illustration and their participation in this field is less tangible and more inferred. How do you know the difference between a maker or manufacturer who actually makes real combat knives and the company that just makes the claim? Hold on to your hat: it's the sheath. If a maker or company is making an actual combat knife, the sheath is just as important as the knife, and made just as durable, with specific and various options, with real mounting and interfacing hardware to work with the professional's gear. How do I know this? Because this is how every knife makes it into battle: in a sheath. So don't forget to look over what is (or what is not) offered in this critical part of the knife package; it will tell you a lot!

Most knifemakers and manufacturers who overly hype their steel type produce an inferior product.

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"PJ" fine handmade custom CSAR knife, obverse side view in 440C high chromium stainless steel blade, 304 stainless steel bolsters, canvas micarta phenolic handle, locking kydex, aluminum, stainless steel sheath with ultimate belt loop extender and accessories
The tough, corrosion resistant and hard use tactical combat and rescue knife "PJ" with 440C blade

Why the bad rap from knifemakers?

440C is a good, proven, and highly corrosion resistant tool steel, with a long history of reliability, used for many industrial applications as well as in fine handmade custom knives. It takes and holds a great polish, is highly resistant to corrosion with minimal care, and is a very tough, wear resistant, and dependable high chromium steel. Many of the best knifemakers in the world use or have used this steel.

Why the bad rap from knifemakers, when this is the standard to which all other knife blade steels are typically compared? Here are some things to consider:

  • The maker may have no familiarity with 440C, and have never used in in a project.
  • The maker thinks 440C is old, common, and frequently used, so is passé.
  • The maker may not be able to use 440C, because he is hand-forging knives, and 440C can not be hand-forged in an open-air forge.
  • The maker may not heat treat his own blades, or has had difficulty heat treating 440C.
  • 440C must be heat treated in a purified, restricted, or non-decarburizing atmosphere to preserve its alloy content.
  • For ultimate in performance and response, 440C must be heat treated with cryogenic process and deep thermal cycling only available with cryogenic equipment and high purity and immediate processing.
  • 440C is not a forgiving steel; once it's hardened, there is typically no correction, no turning back, no adjustment to the machining, shape, linearity (straightness) or form of the blade apart from grinding with super-hard abrasives or carbide.
  • 440C is difficult and challenging to mirror polish. I've known plenty of professional full-time knifemakers who cannot achieve a mirror finish on 440C, so they don't use it.
How does 440C receive a bad rap from knife owners who are not impressed with its blade performance?

I've received plenty of emails and heard plenty of times in the history of my nearly four decades of making knives that someone has purchased a knife made from 440C and the performance was less than satisfactory. Please note that I've received plenty of comments that my own 440C knives are outstanding and the performance is superior. Disgruntled 440C blade owners may go on to claim that all stainless steel is bad (more on that topic here), or that 440C is not suitable for good knives. This is bunk, and they are misinformed. However, I believe I know why this happens, and it happens a lot.

440C can be incorrectly processed, and this occurs frequently.

A very well-known maker I know heat treated his 440C in a plain furnace. The furnace was actually a refitted casting burn-out oven and there were no special precautions or processing; the knives were in atmosphere. This means that the blades were not protected from harmful oxygen during the heat treating process. When this is done, the carbon in the steel migrates to the surface of the metal and forms a hard, carbon-bearing crust of scale that is extremely hard and difficult to remove. This effectively lowers the carbon content in the steel and the 440C becomes equivalent to 440B, 440A, or worse. There isn't much carbon in tool steels, and any change in this content will result in markedly lower performance characteristics (wear resistance) because less chromium carbides are formed, and less martensite overall. This maker's blades decarburized. Just to be clear, the Machinist's Guide and other steel authorities and organizations list decarburization as the number one cause of bad heat treating results. This lowered the performance of the blade. Another issue is that his oven was painfully slow. It took him many hours to achieve critical austenitizing temperature which allows even more carbon the time to migrate in the steel. It also caused extensive grain growth, weakening the steel overall. Then, he held the critical temperature for far too long, thinking that extended time will assure more transformation and thus a more uniform and robust martensitic structure, but instead, this allows even more carbon migration and grain growth to occur! Then, he simply air-quenched, a slow, leisurely cooling without interrupted quenching, freezing, or other procedures that can maximize hardenability. He tempered only one time in a toaster oven or his kitchen oven, so his tempering temperature and heat distribution were tenuous, uneven, and uncertain, since these ovens are not calibrated and do not offer truly even, regular, and non-spiking temperatures as a professional heat treating oven would. An additional between-temper freeze, cryogenic processing, and a second temper with deep thermal cycling were never done. Needless to say, the best processing in 440C happens in three temper cycles, not one. Incomplete transformation, uneven carbide distribution, decarburizing, high retained austenite, grain growth, missed tempering, and other process failures accompanied every single one of this man's knives made of 440C. He did do a good polish though (which was easy because the lower carbon makes less of those pesky chromium carbides that are hard to smooth). Now, this man was not some yokel who dabbled on the edge of knifemaking; he is one of the most popular knifemakers who ever lived. And yet every knife he made of 440C was poorly processed, and lacking in performance. No wonder 440C gets a bad rap!

Simply put, 440C is difficult to work with, and hard to finish, and there is a lot of 440C out there that was not correctly processed. This doesn't make it a bad steel, it means the knifemaker was careless. I believe this is one of the main reasons 440C gets a bad rap in some collector's or knife user's circles.

Finish value is rarely discussed by novice or unskilled or non-professional knife makers and is never discussed by any factory, because these groups never, ever finish a blade, simply settling for sanding to 320 grit like a piece of pine in a weekend hobby project. Manufacturers don't finish anything; they mass process with automated machinery and then get the product out the door. Since 440C excels in corrosion resistance when mirror polished, and since they never mirror polish, any evaluation or comparison of corrosion resistance is meaningless.

Why don't they mirror polish? Skill, that's why. It takes a lot of time, patience, effort, and skill to properly mirror polish any blade, but that is how all of the finest investment grade knives reach their zenith. You'll see a lot of guys justifying why they don't mirror polish, and most of it is lack of skill and patience. More on that in the topic below: What about working with 440C?

The reason some of my own knives are not mirror polished is simple: the client requests a flat finish because he does not want reflectivity (usually military or combat knives) or he can't afford the extra expense of a mirror polish. That's it. You'll see that the collaborative works on this website with new makers do not have a mirror polish because they do not have the skill level yet to attain a mirror polish and appropriately. Practice, skill, and patience build in this field and I'm confident that determined other makers will attain this highest of desired finishes, but MOST other makers in the world do not bother. They simply choose not to mirror finish. When making this choice, they have no real standing or experience in evaluating or judging a steel like 440C on corrosion resistance since this is where 440C shines.

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Note! (to knifemakers)
Follow Directions!

I've noticed that this page gets a lot of attention from knifemakers, and discussion goes on and on about this steel, how to heat treat it and what to expect. This can get out of hand, with guys claiming to know special bonding structures of the grain, grain size and shape, and describing various methods to achieve certain invisible, unproven, and ridiculous results (more on "grain" ignorance here). Here's my take on this:

Heat treat each piece of 440C according to the manufacturer's directions. THAT'S IT! You don't have to try to better their process; the foundry knows how they made the steel and they politely and effectively tell you how to heat treat it for the best performance.


All 440C is not the same! Since minor variations in the alloy content are certain to occur as a result of foundry process, as a knifemaker this is not your concern. Just heat treat the steel according to the manufacturer's directions.

Good grief, it's easier than baking a cake! When you bake a cake, you have to measure and mix the ingredients, and the foundry has already done this for you!

If, as a maker, you think that you have some better process than the steel supplier, please do tell them your discovery, maybe you can become a metallurgist or engineer. Also be sure to tell every machine shop and industrial manufacturer of machine tools, dies, valves, shears, forms, presses, and every other industry that uses 440C. Wait. Do you suppose that these professional industries already know how to achieve the best performance in their steels? Then, who do they get their heat treating information from? Could it be the supplier of the steel? Ahem.

Just follow the steel supplier's directions.

I don't know how this could be simpler. And then spend some time on Fit, Finish, Balance, Design, Accessories, and Service, as these are the real limitations for most knifemakers today.

"Titan" kerambit, obverse side view in 440C high chromium stainless steel blade, hand-engraved 304 stainless steel bolsters, Crazy Lace Agate gemstone handle, ostrich leg skin inlaid in hand-carved leather sheath
The vicious and elegant curves and polish of this "Titan" in 440C

Wives' Tales, Myths, and Misunderstandings about 440C
and other steels

There is a lot of misinformation, misunderstanding, confusion, and errors in our world, and being the communicative species we are, it's best to try to reach the truth, since any other conclusion simply leaves us floundering in ignorance. In this section, I'll expand on some of the things I've heard or read, and questions that people have asked, and the curious misunderstandings that pop up. Please notice that I'm not calling these lies; lies are purposeful acts that are known to be untrue, and are usually perpetrated for the benefit of the liar. I'll be more diplomatic, since people who hear or read falsehoods are not responsible for what they've heard, and they simply want to know the truth.

Hi Jay,
Firstly I really apologise this is a question I cannot find an expert who can answer and I am hoping you may reply with a simple yes or no?
I have been told a knife made out of 440C will go blunt just sitting doing nothing but being exposed to air inside a house. Apparently this is due to the chromium slightly dulling the edge as it protects the steel from air inside a house. I can understand this outside in a damp area, but, not in a house. Is this true?
I really would appreciate if you could respond to this.
Regards, S.

I decided to elaborate on this concept, since I've heard it before. While the concept has some fundamental basis in physics, the answer is clearly NO.

I believe this idea is birthed from the fact that when stainless steels are first cut, ground, or exposed to oxygen (in all air, whether it's inside a house or not), they instantly form a passive oxide surface, and this is what inhibits corrosion of the metal. So when a knife is sharpened, new metal is exposed, and the passive oxide instantly forms this surface. There are several errors in logic that occur with "exposure dulling." While it happens, it does not happen with stainless steels, only non-stainless steels.

The first error is believing that stainless steel takes a while to form the oxide layer, therefore if it sits a while, the layer will form at the very cutting edge, dulling it. This is not true; the oxide surface forms instantly upon exposure to oxygen. When a knife is sharpened, it does not change in edge quality, corrosion resistance, accuracy, or geometry simply by sitting in air.

The second error is believing that the oxide film or surface on stainless steel has enough thickness and mass to change the quality of the cutting edge. The surface film formed on stainless steels is a thin, tightly adherent layer of oxide, actually Cr2O3. This is chromium oxide; it is tremendously stable and hard, and in native stainless steels is about 2 nanometers thick. While that translates to 2000 picometers, it is finer than a STRAND OF HUMAN DNA! So unless you plan to cut extra large DNA in half with your knife, the formation of the chromium oxide layer will not effect the size and thus shape or nature of the cutting edge. More on sizes of particles and the nonsense associated with them on this topic on my "Blades" page.

Damp air may be a concern with carbon steel knives, and knives made of lower chromium content than 440C, but rest assured that damp air has no bearing on 440C's corrosion resistance at the cutting edge. When steels have at least 11.5% of chromium, they have aqueous corrosion resistance, and then are deemed "stainless steels." They are passive in aqueous solutions, and 440C has about 17.5% chromium, so damp air has no effect on this steel whatever! Damp air does have a corrosive effect on carbon steels and non-stainless steels though, as they can sit in damp air and corrode and rust, dulling the blade! Perhaps the person who wrote this is referring to 1095, 5160, and all the hypoeutectoid darlings of the hand-forged crowd. But 440C and all other stainless steels laugh at the damp air argument.

Simply put, 440C and other stainless steels do not dull by sitting in air. Now you know technically why this is so.

Please help to stop wives' tales, knife myths, and misconceptions in our trade through education.

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No corrosion on this fine chef's knife razor edge:
"Concordia" obverse side view in 440C high chromium stainless steel blade, 304 stainless steel bolsters, Nebula Stone gemstone handle, stand of American Black Walnut, Poplar, Nebula Stone, Baltic Brown granite
More about this "Concordia"

More About Toughness and Ductility

If making a knife is a choice of economy first, and performance second, low alloy carbon steels may very well be the best choice. But that's not a reason to make knives by hand at all, for the world is full of cheap, low performing knives.

If you are a knife client, please know that I've added this topic to this page on 440C high chromium martensitic stainless steel because guys that like to hate 440C don't bother to read the "Blades" page, and they stubbornly refuse to learn. They spread a lot of misinformation and you deserve to know the truth. They are often hobbyists, uneducated and/or inexperienced and get the majority of their information from the forums and discussion boards on the internet, where like-mined hobbyists also post. I've read humorous and sad posts on this topic over and again from guys who hammer (or use an electrically powered trip hammer) to forge carbon steels, and still claim that this 17th century technology (apart from the electricity and natural gas they use) creates blades that are somehow superior to modern 21st century tool steels used in modern metallurgy and machinery. It doesn't help to tell them that the most advanced performers are high alloy hypereutectoid stainless steels; it doesn't help them to know that they are aerospace materials listed by the  American Iron and Steel Institute (AISI), the Society for Automotive Engineers (SAE), and the American Society for Testing and Materials (ASTM), and Aerospace Materials Specification (AMS) sources for a reason, and that reason is performance.

They will even go on to blame me for simply claiming what is the truth about high alloy steels, and it's sad and insulting to our tradecraft, industry, and art to see this go on and on, decade after decade. The claims they make are not rooted in any science, metallurgy, technology, or experience: they are simply repeating what sounds good to them as they justify the reasons they make knife blades from poor, cheap, and low alloy steels.

One of the major misunderstandings in this subject is toughness. The equation of wear resistant high alloys = brittleness is the same that I hear about gemstone: if it's a hard stone, it's brittle and will break. Even though stone is the absolutely longest lasting material ever used on any knife, and even though high alloy steels are the longest lasting, most wear resistant, strongest, most durable, corrosion resistant and tough materials humanity currently makes for this application, these myths continue! These guys will deny this obvious truth, spreading misinformation, in order to make their work more desirable and keep their clients in the dark. They do it with each other, with anyone who will listen, and with a client who deserves better.

Toughness is not the superior domain for low alloy steels; toughness is set by the maker, and for all steels properly hardened and tempered, the high alloy hypereutectoid and stainless steels will absolutely be tougher than all carbon steels. Otherwise, engineers, machinists, and the military industrial complex would be using only low alloys. They only choose low alloys for one major reason: they are cheaper. They are not superior in toughness, not superior in wear resistance, not superior in corrosion resistance, or any performance aspect but one: economy. In machinery, it's a matter of using the cheapest material possible to do a job, and if a job has to be performance based, the material choice overrides that economy. It then stands to reason that if making a knife is a choice of economy first, and performance second, low alloy carbon steels may very well be the best choice. But that's not a reason to make knives by hand at all, for the world is full of cheap, low performing knives.

So, here, again, is the truth about toughness:

There is often a lot of talk and a lot of confusion about toughness in this field. Knifemakers can endlessly discuss the merits of their particular steel choices (I can too!), and toughness plays a critical role. It's not enough to make a knife hard and wear resistant, it must be tough enough not to be brittle. No one wants their knife to break or chip, yet they want it to be as hard and wear resistant as possible. This is the ultimate balance concept and some makers and manufacturers think that this balance is derived from simply the steel choice alone. Choose the "right" steel and you get hardness and toughness together in some grand and universally superior combination, and can then forget about other steels, other steel properties, and even the knife type and geometry itself.

Denier's Rule 16: "High alloy steels are harder and wear resistant, therefore must be more brittle."

This Denier's rule is so often repeated (mainly on forums) that knifemakers and knife enthusiasts actually believe it. They go on and on explaining how hardness is somehow a problem, not understanding the entire relationship of hardness and toughness, when it's really very simple. The knifemaker can set the hardness and the toughness anywhere he wants within the capabilities of the steel. He can make an extremely hard blade that is extremely wear resistant, and he can also make a blade extremely tough and less wear resistant, but less likely to break. The knifemaker sets this relationship and balance; it is his domain and his responsibility.

A lot of makers like to justify why they don't like high alloy and stainless steels, claiming they are too brittle for use, and they are flatly wrong. The reasons that high alloy steels exist is because they excel in most characteristics (wear resistance, toughness, and corrosion resistance), and they excel in measureable and proven ways. Otherwise, they would not be manufactured, made, or used! Why even make high alloys unless they are superior? Why not just opt for the cheap alloys and spare the expense? Why would die and mold makers, cutting tool makers, and other real industries rely upon high alloy steels in the first place? Worse, why deny the value of an extremely high performance blade to a client? Why try to convince clients (and other knife enthusiasts) that somehow, lower alloy carbon steels are a better choice?

Here's the really important point:
With proper geometry and heat treatment, high alloy steels excel in both hardness and toughness in every application.

Otherwise, they would never be made at the foundry, never used on any device or machine, application, or circumstance. Alloy sets would not continue to evolve and be developed, and we would be living in the late 1800s where the best steels would be hammered out on an anvil. Do you honestly think that modern metallurgy does not have a grasp on why high alloy content is important and beneficial? Do you think the highest wear, highest toughness applications of tool steels are served by lower alloys? Perhaps you believe that Japanese sword smiths working 1000 years ago knew more than modern metallurgists. Don't laugh; some people actually believe this Hollywood fiction.

Let's look at toughness a bit more, since this is what some makers claim is a problem with high alloy steels. Granted, some steels are better used in high wear applications with limited toughness, and some steels simply can not be made hard enough for high wear applications, but it's in the knifemaker's domain and it's his responsibility to explain this to his clients and users of his knives.

toughness, adj.
  1. (general) Able to endure strain, hardship, or severe labor.
  2. (metals) The ability of a metal to deform plastically and to absorb energy in the process before fracture
Source: Webster's International Dictionary, 1828-present, AISI and engineering sources

As I've written over and over, there are many types of steels for a reason; they all have specific properties, and those start with the alloy content. Lower alloy steels are lower alloy for a reason (usually economy), and because the uses they are designed for do not require the more expensive higher alloy content, the higher cost of machining and working, and the higher cost of proper heat treating and processing.

But where, specifically does toughness fit in? Are lower alloy carbon steels tougher than high alloy and stainless steels? Does the mere existence of chromium or other alloy elements in steel knife blades mean a blade is by its very alloy, less tough? No it does not, and it's time this misconception is cleared up.

When makers discuss toughness, they often make the comparison of carbon steels and stainless steels in a rough and indeterminate fashion, making claims that lower alloys are by nature of their elements tougher, which is in error. They do this because they think that higher alloy content which can result in a blade that has high hardness and high wear resistance is therefore more brittle. A more brittle blade is more apt to break, so the hardness-toughness pendulum must swing in favor of a lower alloy when toughness is paramount and desirable.

This is a zero-sum game and is a fallacy. The increase in wear resistance of higher alloy steels is not just derived from high hardness; it's derived from carbides, martensite, and the structure of the steel. Substantial gains in hardness and therefore wear resistance does not, by necessity, mean a high alloy blade is less tough. In fact, most of the high alloy hypereutectoid stainless steels are also much tougher than the lower alloy carbon steels, even at higher hardness! Add to this the misperception and confusion about how proper Heat Treating and Cryogenic Processing of Blades also increases toughness, and it's easy to see why they are confused about toughness.

Frequently cited for example is a sword blade which must be fairly tough and somewhat springy, so that it will flex without breaking or chipping. It doesn't help to see a frequently linked YouTube video of a cheap Chinese-manufactured attempt at a sword, breaking when slammed into a table, but this is not how the best knife or sword blades are made. Yet these anecdotal demonstrations of poorly made junk are frequently used to bolster arguments by the ignorant, because after all, a video is easier to look at than reading and study, which requires interest and critical thinking.

On the surface this poorly perceived "toughness limitation" of higher alloys seems to make sense, but let's look a little closer. Toughness comparisons are somewhat relative, and there is a lot of confusion about what constitutes strengths, durability, and performance in steels. Knifemakers seldom consider critical performance studies, scientific articles, and scholarly research, and yet claim to know what is simply the best steel for the knife based on their own preferences. I'll flatly claim that their preferences are chosen because of their own comfort and familiarity of their steel experience, and this does not translate, necessarily, to a benefit for the client. As a professional, this field is about the client, not the maker, and that is why I try to work with many types of steels to offer a wide variety of options.

Toughness is not a singular concept, and that is the first consideration. Metallurgists consider stress-strain curves, moduli of elasticity, stiffness and failure rates for an incredible amount of steels to determine their performance value, and though knifemakers are only usually considering a few of these applications, it helps to understand a bit about how they all interrelate.

When knife people discuss toughness, they must, by necessity include the discussion of ductility.

ductility, adj.
  1. capable of being hammered out thin, as certain metals; malleable.
  2. capable of being drawn out into wire or threads, as gold.
  3. able to undergo change of form without breaking.
  4. capable of being molded or shaped; plastic.
  5. most importantly in this context: In materials science, ductility is a solid material's ability to deform under tensile stress; this is often characterized by the material's ability to be stretched into a wire.

Ductility is the measurable ability for a material (steel) to deform before rupture under tensile deformation. Consider a wire that is stretched until it breaks. it moves, it deforms, it's bent, strained, stretched and then finally it breaks. The measure of stretching is the percent elongation, defined as the maximum elongation of the section (gauge) length divided by the original section (gauge) length. So, in determining the ductility of a steel type, a wire is stretched until it breaks and the ductility is measured as a percentage of elongation.

Toughness is likewise measured, and can be considered ductility with strength. Toughness testing usually includes impact in testing apparatus, either in the Charpy test or Izod test. Both tests only measure the relative toughness of materials in a very specific application that is not a knife blade! This is important to understand, because knife blades are very specific use items, and are not blocky notched pieces of metal that are typically the form that is tested. In both of these tests, a pendulum is swung into a notched bar, until fracture, and the energy absorbed in the fracture is determined as a ratio of the height and weight of the pendulum as a calculation of initial energy vs. the absorbed energy.

But what does all of this have to do with knife blades? Here is the problem: knife blades and the steels used to make them do not fall under one concept, one test, category, or issue. For instance, consider that the overall durability of steels in knife blade performance are determined by these factors of strength alone (from the Machinist's Guide, AISI, SAE, ASTM and ANSI):

  • Stress per force of unit area
    • tensile strength (always considered at right angles to the area being considered)
    • compressive strength (always considered at right angles to the area being considered)
    • shearing stress (always considered in the plane of the area being considered)
  • unit strain: the amount by which a body changes when subject to a load
  • proportional limit: the point on a stress-strain curve at which it begins to deviate from the straight line relationship between stress and strain
  • elastic limit: maximum stress to which a test piece is subjected to and will still return to its original length upon release of load
  • yield point: the point in a stress-strain curve at which there is sudden increase in strain without an increase in stress
  • yield strength: the maximum stress that can be applied without permanent deformation
  • ultimate strength (sometimes called tensile strength): maximum stress value obtained on a stress strain curve
  • modulus of elasticity: the ratio of unit stress to unit strain within the proportional limit of a material in tension or compression
  • modulus of elasticity in shear: the ratio of unit stress to unit strain within the proportional limit of a material in shear
  • Poisson's ratio: the ratio of lateral strain to longitudinal strain for a given material subjected to uniform longitudinal stresses within the proportional limit

These are just a few strength forces and considerations. Add to them compressive properties, shear properties, fatigue properties, influence of mean stress on fatigue, cumulative fatigue damage, and many and numerous modes of fatigue failure like low and high cycle fatigue, thermal fatigue, corrosion fatigue, surface or contact fatigue, and combined creep and fatigue which is an interaction not even well understood!

So what does all this have to do with knifemaking and knives in general, focusing on steel types for specific applications? After all, most knifemakers are not mechanical engineers, yet work in the very realm where many of these factors are in play.

Toughness and ductility are not the be-all, end-all factors in knife blade construction. Unless you are using a knife as an axe or machete, toughness is usually a secondary consideration to hardness and wear resistance. Most modern high alloy steels can be very hard and very tough, together. Most clients prefer a blade that has a long-lasting cutting edge, not a soft or ductile edge that rolls, bends, or deforms. A softer (and tougher) edge may require more maintenance, and more care and more sharpening while usually being less wear resistant. This is why high alloy steels are used for industrial blades, after all, not lower alloy and more ductile steels. More ductile steels are used for impact-exposed tools like air chisels and economical ball bearings. If lower alloy steels were better performers, we wouldn't even have the high alloy steels!

All the knifemaker can do is make the best choices he can for the specific application, create the best geometry for the blade's intended use, heat treat and process properly for the best hardness-toughness balance, finish the blade to its highest potential, and complete the knife with applicable and sturdy fittings, handle, and accessories.

How does the buyer of the knife determine this? Simply by experience and logic. There is no ultimate answer, not miracle steel or treatment, and the maker himself demonstrates his experience in the knives he creates and the people who use them.

Now the really important part of this, directed at the person who is interested in acquiring the very best knife possible: For all these discussions, take some time to look at the track record, history, testimonials, and above all the knives and sheaths and accessories of the maker. Look at his knives. Look them over good. Does the skill and knowledge he expresses in discussing engineering and metallurgy present itself in his works? After all, that's what really counts!

For the knifemakers: I've seen discussions online about the relative toughness, strength, and shear or various carbon steels where makers have claimed superiority of these steels to our old favorite reference steel, 440C. Just so you have some numbers to chew on, here are some simple specs that should clear up just exactly what is the toughest steel in this selection (from AISI, ANSI, and other official engineering and metallurgical sources you can reference yourself):

Steel Type Fracture Toughness (Max) Shear Modulus (Max) Ultimate Tensile Strength (Max)
52100 18.7 MPa-m½ 80.0 GPa 195,000 PSI
1095 18.7 MPa-m½ 80.0 GPa 184,000 PSI
440C 24.2 MPa-m½ 83.9 GPa 286,000 PSI

For those who claim that these carbon steels are tougher than 440C, this should clear up that misconception.

As a humorous note, an anonymous poster claimed that this chart was not valid since the hardness of each steel listed in the chart was not specified. Just to be clear, what is listed is the "Ultimate Tensile Strength," meaning the greatest, and "Max" means the maximum possible in the alloy. I think that's pretty clear to most readers.

Toughness and hardness are considered together in the ultimate tensile strength, according to ASTM and ISO standards.

"A strength is nothing more than a stress "at which something happens" be it the onset of nonlinearity in the stress-strain response for yield strength, the maximum applied stress for ultimate tensile strength, or the stress at which specimen actually breaks for the fracture strength."

--University of Washington,
Mechanical Properties and Performance of Materials
Mechanical Testing

This is the reason that Ultimate Tensile Strength is not considered by fracture toughness alone, or by hardness alone, or by geometry alone. Otherwise, we'd have to conclude that wire rope would make a much better knife (because it's tougher), and spider web would make the best knife of all, since it's the toughest. Oh, snap! Revision! The tooth of a limpet (an aquatic snail) has now been determined to be the toughest natural material! Let's make knife blades out of that!

By the way, toughness is NOT the main consideration in knife blade performance, wear resistance is. If you are using a knife as a chopping tool, it's best to get a $5.00 machete from the hardware store (in the lawn and garden department) to use for your chopping. That way, edge retention is not important, and you can whale away on your shrubbery, or beer cans, or 2 x 4s to demonstrate the chopping ability. Hint: I've never had one counterterrorism or combat knife client request a "chopper." Nor has any professional restaurant chef. Nor has any professional guide. Nor a collector. They all cite wear resistance first, and corrosion resistance second, and toughness third in their knife blade considerations.

Please help to stop wives' tales, knife myths, and misconceptions in our trade through education.

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"Bulldog" obverse side view in 440C high chromium stainless steel blade, hand-engraved 304 stainless steel bolsters, Fossilized Stromatolite Algae gemstone handle, hand-carved leather sheath inlaid with burgundy ostrich leg skin
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What about working with 440C?

Some people like 440C, and some don't. Because it's my most often used knife blade steel, it's clear that most of my clients prefer 440C. I've made thousands of knives with this steel, and because I've made so many knives for so many years, and because what you are reading here is fairly popular in my field, my name gets associated with 440C as is I am somehow bonded with this steel. The people who tend to make that type of claim are usually hobbyist knifemakers, or anonymous posters on forums who don't have anything to do with my particular tradecraft, art, or business. They never seem to decry or complain about my use of or pages about the other dozen steels I use, steels like ATS-34, D2, O1, and CPM154CM. They don't complain about my use of and information about CPMS30V, CPMS90V, CPMS35VN, N360, or CTS-XHP. They do complain about this very page about 440C, which reinforces the concept that this very particular steel is the focus of a love/hate affair. You don't seem to see this type of polarity about other steels; knifemakers will discuss the pros and cons of them without emotion. But that 440C, well, darn it, they don't like it, and don't think anyone else should be using it!

This strange reaction has a basis in several factors in my tradecraft, and these are not often spoken of, so since this page is about this very contradictory perception, I'll elaborate on what I know, and what I have experienced in this field. If you are reading this, you deserve to know some specific working properties about 440C and its use in hand knife blades, so my hope is that this may answer some of the questions about the curious reaction a simple steel type gets in this field.

440C is hard to cut; it's hard to grind, and it's hard to finish. If you know something about fine handmade knives, you well know that some of the greatest knifemakers who ever lived in in recent times have used this steel, so it's not an impossible steel to work with, and it's evidently highly desirable to the people who have purchased these knives, some of the best knives ever made in recent times. Just look up some of the great masters of knifemaking and you'll see 440C pop up over and over again. Having worked with many different kinds of steels myself, I'll make it clear that 440C is a very stubborn, very tough, very difficult steel to cut and grind. It's probably due to several reasons, and perhaps it's the way the foundry has offered it, but it's very tough stuff.

Comparing the hardness of a few steels before heat treating may give an idea of this. CPM135VN is a very high alloy powder metal technology tool steel, and it's difficult to work with. It comes from the foundry where I acquire it at about 25C Rockwell. CPM154CM is likewise a powder metal technology tool steel, and it comes from the foundry at about 18C Rockwell. ATS-34 is a high alloy, high chromium and molybdenum tool steel and comes in at about 12C Rockwell. 440C comes from the foundry at about 5C Rockwell, almost dropping off the scale. Yet of these four, the most difficult and stubborn to cut, drill, and machine, the steel that demands more actual cutting current on a electric bandsaw with the thickness, feed rate, and all other factors being equal is 440C, even though it's much softer in its annealed and spheroidized state! Why?

I can only surmise that the relative toughness in machinability is because of the high content of chromium in this steel. It could also be the size of the chromium crystals, or their distribution, but the important thing to remember is that chromium is the hardest metal on the periodic table, and it is a true refractory metal. Of course, you won't see increased penetration testing numbers (Rockwell) in an annealed and spheroidized piece of steel, because the chromium is only 18 percent of the material and the steel is annealed. Add to that the spheroidized condition, and the very hard allotrope and alloy elements created during proper processing of this steel (martensite and carbides) are not present. Even though, 440C is difficult to machine in the softest state, and it's almost certainly the high percentage of chromium.

The critical point here is that 440C is very difficult to work with. It's very tough, an obstinate material that is resistant to cutting, grinding, and forming, drilling, sanding, and finishing. I believe this is one of the reasons that a lot of knifemakers do not like it. They've tried to work with it, or a buddy has, and it's just that difficult. Why not come up with another material that works easier? Why not use something that cuts fairly smoothly, evenly, and finishes with less effort? That would be ATS-34 and CPM154CM, and all carbon steels (hypoeutectoid plain carbon steels). They are easier to work with, and after all, knifemaking is all about easy, right?

By the way, there is a common paragraph about O1 that's been circulating on the internet for decades, where a former maker (and dealer) of knife supplies claims that O1 is harder to grind than 440C, but this is just flat out wrong. O1 is like working with butter when annealed; maybe the O1 this guy was using was already hardened and tempered, but even in this condition, O1 works far easier that 440C at the same hardness. Having made hundreds of knives with both steels, I'll claim that this is the reality.

While steels like D2, CPMS30V, and CPMS90V are harder to cut, grind, and finish a knife blade with, they are usually never finished beyond sanding. CPMS90V and CPMS30V can't be mirror polished, and neither can D2, since there is such a profound chromium carbide granularity in the finish. Clients who request 440C often do so in mirror polished works, because that is where this bright, bluish chromium steel excels in corrosion resistance. So it then comes down to the grinding and finishing. If a knifemaker is not good at, or comfortable with standing for hours in front of a grinding machine, slowly and carefully creating an accurate knife blade, he may well look for a shorter, easier way of doing things. 440C is not his game.

I once had a couple makers come to my studio, and one of them was a past president of the most popular hand-forging knifemaking organization in the world. I showed them what I was working on and showed them some 440C blades I had finished. This master (and he was a true master at his tradecraft and art) was amazed, and gawked at the beautiful mirror polish on my blades.

He asked, "How do you do that? I've worked with this stuff for years and I've never been able to get a finish like that!"

He went on to explain that he'd given up on 440C because he couldn't make it look as good as old so-and-so's knives (or my knives). I told him that it's a fairly straightforward, but long process. I grind the master grinds at 60, 80, 120, and 180 grit, then I heat treat, and then I control grind at 220, 320, and 40 micron, and then I finish grind in 30 micron, 15 micron, 9 micron, and 5 micron, and then I polish (in two separate steps). Every single scratch or mark from the previous grinding step has to be removed, in the grinds, on the flats, the swage, and the spine and tang. He said that he didn't want to do that much work...and this is why he chose not to use the steel.

Another plain fact is that guys want to sell the knives they make, and not necessarily the knives their clients desire. This is one of the most important things a professional can do: listen to his clients and make what they want. Do you honestly think that the many hundreds of made and sold 440C blade knives on this website are not desired and paid for by clients? Have you read the testimonials? Is it so hard to understand that they desire the highest corrosion resistance and extremely high wear resistance with high toughness that this steel offers (when properly processed)? By the way, my clients ask for all types of steel, and 440C is only one of the high alloy steels I use, but it's the most often asked for.

Other knifemakers may not want to use this steel, and don't want to have to use this steel, and may not have the equipment or experience to correctly process this steel, so they try to dismiss it and impugn others who use it. You may say that I dislike hypoeutectoid low alloy carbon steels, but I don't; it's just that I believe the finest knives deserve better steels. The difference is that the technical details of all of these steel types are well known by machinists, metallurgists, and industrial professionals, but these easily located facts seldom make their way into the conversations knifemakers have, and it does our industry no good. Do you suppose the same makers who decry the use of 440C also impugn the military, the aerospace industries, and machine shops that use this very well-known steel? Do they claim that the engineers who build high pressure valve seats, needle valves, ball check valves, turbine components, oil well pump parts, chisels, cams, medical instruments, corrosion resistant molds and cutting shear blades, aircraft landing gear, corrosion resistant ball bearings, and uncounted other heavy use industrial and aircraft steel parts don't know what they are doing using 440C? No; it's much easier to attack a single knifemaker who lists the extensive advantages and limitations of several types of knife blade steels on his website, because he's an easy target, so my name seems to come up often when they try to demean the use of this steel alloy.

"As far as rocket engine turbomachinery systems are concerned, 440C is generally considered to be the best compromise between corrosion resistance, fatigue life potential and other material properties. It has been used as the bearing material in most production cryogenic turbopumps, especially those involved in moving liquid hydrogen. The fuel and oxidizer turbopumps fof the J-2 engine both used 440C as bearing material as do all four turbopumps for the Space Shuttle main engine."

--Handbook of Turbomachinery
Earl Logan, 2003

From this section, what I want you to consider is that it could be that some of the resistance to the use of 440C by knifemakers is because it's a fairly difficult material to work with. This combined with the section above on proper heat treating and processing of this steel, and the intelligent person can see how one steel may become polarizing, particularly to those who have little experience using it, and lack the equipment and knowledge to properly process, harden, and temper this steel. For clients and knife users who want a blade steel that is highly corrosion resistant, one that wears extremely well, one that is tough and durable, 440C is well within a proven range of use and application. While many of the dozen or so steels I use meet this criteria, 440C has a great balance of all of these properties.

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"Edesia" fine handmade cleaver, obverse side view in 440C high chromium stainless steel blade, copper fittings, olive hardwood handle, hand-tooled leather sheath
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Some Metallurgical Questions about 440C and Heat Treating

Below are some questions about heat treating 440C from my "Heat Treating and Cryogenic Processing of Knife Blade Steels" page. On that page, I write about many steel types, and along with the "Blades" page, the amount of information can be overwhelming. I thought it would be important to repeat some of the 440C-applicable subjects on this page. For more information, please visit the two pages listed; once you read them, you'll know more than most knifemakers about heat treating and knife blade steels; I promise!

I'll post more questions and answers about 440C as time allows. Thanks!

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440C and Quenching Methods

Here's a great email from a chef who has invested in learning about heat treating in his search for the very best, high performance knives:

Hi Jay,
Just a quick note thanking you for your recent YouTube videos!  I've learned so much about heat treating and knife steels from you.  Unfortunately, I think they ruined me.  I just got off the phone with another custom knife maker who uses 440c in most of his knives, and he was bragging about his heat treat.  He says he gets his blades to 63 HRC by quenching them super fast.

In the back of my mind I could hear you cringing and reiterating the 4-5 degree F temperature change per minute rule for optimum Martensite formation.  He didn't even mention the Martensite finish temperature or carbide formation at shallow/deep cryogenic temperatures.

Needless to say, I now have a very limited number of knife-makers I can buy from in good conscience.  I know you're very busy, and I don't want to sound desperate, but PLEASE, post some chef knives on your website soon! (ok, I admit it, I'm desperate)

Thanks again for your videos and all the great info on your website.  I hope to be a future customer soon,


Hi, A. Thanks for writing; I understand your dilemma!

It’s not my intent to spoil knife owners and users to only the very best premium treatments; I know that few makers and no manufacturers perform premium treatments; I just want people to understand the range of processes and why some are better or worse than others. While it would be great if knifemakers thought more like metallurgists and scientists than casual craftspersons, I realize that this is not in the scope of many knifemakers’ interest.

As far as the individual maker you’ve mentioned and his process, I do hope that in the videos I’m being clear, and I’ll touch on this very subject in the next video that I do. Initially, the quench from critical temperature to room (ambient) temperature is fairly fast (and not 4-5 degrees per minute). For 440C, simply leaving sit in still, open room air is typical, but in some circumstances, 440C is actually quenched in oil. The slower rate yields a slightly lower hardness, and the faster rate of an oil quench gives a slightly higher hardness, but comes with the possibility of warpage, quench cracking, microscopic fracture, or internal stresses in the steel that can lead to problems down the road. The 4-5 degrees Fahrenheit per minute guide is for the transition from ambient temperature to cryogenic temperature, after the initial quench to ambient. Of course, if he's not going cryogenic, the 4-5 degrees per minute rule won't apply...

Did you know that the critical (austenitizing) temperature has a lot to do with “as quenched” hardness? In any case, the hardness when quenched only to room temperature is not a valid indicator of success in heat treating, since the martensite finish temperature of 440C is in the cryogenic temperature range. If the maker is simply quenching quickly to room temperature and then moving to the tempering cycle, he may have an adequate blade, but he will have about 29% retained austenite!

This is why conventional treatment is not premium treatment. The steel may test hard, but hardness testing alone does not equate to wear resistance and longevity of the blade. Of course, if there is no cryogenic processing, there will be no benefit from the eta carbides that result from cryogenic equilibrium (long term soaking) and the blade will be markedly less wear resistant overall and not as tough, no matter what the tempering treatment is.

Again, there is no right or wrong way to process, just substantially different methods with substantially different results!

For my own work, please know that I do have many chef’s knives in the works; a couple are completed and waiting their accessories (stands, rolls, sheaths, or cases) and some are waiting on others that will be joining their groups. Some knives are singular, some are in pairs, some in threes, and one group I’m working on has a dozen different style of chef’s knives—I’m working on it!

Thanks, sincerely,

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Does it help to quench 440C in oil?

In a follow-up email, I was queried about quenching 440C in oil. Some white papers and data sheets include this as an option of quenching. The steel suppliers don't often describe why this is listed, so I thought it was important to include it here.

Do you ever quench your 440C in oil, depending on the intended use of the blade?  Your are truly a blessing and treasure for then knife-making community.  Thanks for posting my email to your website too.  I'm honored to be part of your discussion to bring knowledge and clarity to knife enthusiasts around the world.


The reason that someone would quench 440C in oil is more to gain a deeper hardness in thicker pieces. In a thick piece of steel (think 1” thick), the rate of cooling at the surface is fast enough, but deep within the steel, the rate is much slower. This is because steel is actually a relatively slow conductor of heat, unlike copper, silver, or aluminum which conduct heat quickly. So the heat isn’t carried away as fast in thicker stock, relying only on conduction. In order for the higher quench rate to occur deeper in thick metals, sometimes the oil quench is used, with the possibility of quench cracking. However, since the stock is thicker overall, quench cracking would be diminished as there is more metal to physically support the steel. The only case where this would be an issue would be in steel parts with complex geometries, and knife blades are not complex geometries.

In 440C knife blades and in my own experience, oil quenching isn’t necessary. Knife blades are rather thin, and quench and cool adequately without the added and unnecessary stress of oil quenching. Remember, I'm not writing about oil-quenched steels like O1, but air-quenched, high alloy martensitic hypereutectoid stainless tool steels.

Consider that, in still air or between properly designed liquid-cooled quenching blocks, a 440C knife blade will lose 85% of its latent heat energy in less than 30 seconds, and that's a lot! More important is a smooth transition to colder and colder temperatures, without pause, and into the cryogenic range. Transformation continues until maximum martensite conversion is achieved. Then, held at cryogenic temperatures, eta carbides start to coalesce very slowly at very low temperature equilibrium.

To get a little more technical, once the nose of the TTT curve (isothermal transformation diagram) is passed, there is more time for the steel to be cooled at a slower rate. I don't want to get into this deeply, since this is not my metallurgy class, but generally, the addition of alloying elements increases the hardenability of steels by moving the nose of the isothermal transformation diagram to the right, allowing slower cooling rates for alloy steels to form martensite. This is why these high alloy steels are air-quenched in the first place. The same alloys lower the martensite start and martensite finish temperatures considerably, thus the necessary cryogenic quench.

It's important to consider that fast quenching introduces residual stresses that may not be eliminated by further processing (tempering cycles). Quenching a steel too fast can lead to less-than optimum steel quality and introduce stresses in the microstructure that are undesirable and unnecessary. Some makers use a faster quench as a crutch to introduce higher hardnesses, since they think that the hardness penetration tester is the only indicator of steel quality; it is not.

Simply put,

  • Quenching faster does not create more martensite in air-quenched high alloy steels.
  • Quenching deeper (colder) creates more martensite in high alloy steels.
  • Once the initial quench is achieved, the TTT curve demonstrates a slower cooling regime.
  • Quenching faster is done only in thicker pieces of stock because of conduction limitations.
  • Knife blades are not thick pieces of stock.
  • Quenching too quickly introduces residual stresses in the microstructure.
  • Stresses and deformations in the microstructure are not eliminated by tempering cycles.

For my metallurgists: the optimum treatment for any hardenable steel is to quench at the slowest rate possible to pass on the left side of the "nose" of the TTT curve (isothermal transformation diagram), and stay on the left side of the transformation line until complete martensitic conversion. Eta carbide formation under cryogenic compression comes later...


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"Azuma" fine custom knife obverse side view in 440C high chromium stainless steel blade, hand-engraved 304 stainless steel bolsters, Red River Jasper gemstone handle, hand-carved, hand-dyed leather sheath
More about this "Azuma"

The Mimics

There are people in this field who simply mimic what they have heard. I've seen this for decades in this career field. This website and the book I'm writing are my attempt to clarify what has been misrepresented as fact by the ignorant and their mimics. It happens too often that knife makers and enthusiasts simply repeat what they have heard or read in some vague advertising hype as fact, without ever doing any research. I've even seen guys pretending to be testers and evaluators of knives and performance making ignorant claims as if they are some authority. By the way, there is NO certified, regulated, sanctioned, or official testing authority of ANY knife performance, process, or construction, anywhere on this earth! This is not strange or unusual, there are many fields that this does not exist, like jewelry, screwdrivers, or bronze sculptures. Most of these guys just want free knives and to make a name for themselves. Knife groupies, they are. And if a maker refuses to give them a free (and expensive) knife for testing, I've seen them go on rants about the maker and his knives like crybabies teased by a rattle they can't have (for free).

The mimics are often people who publicly post misinformation picked from false knife critics. My own website, words, and practices of knifemaking have been challenged on plenty on forums, bulletin boards, and through other social conversation means. I expect this; I'm successful, and this is the price you pay for working hard and achieving something. So the mimics will continue to spew their ignorance, based on lack of experience, as most are too lazy to do any actual research, testing, or quality knifemaking on their own.

Thankfully, I have many, many dedicated clients who do their own testing and use in the field, and these are actual trials of these critical tools in combat, rescues, working, and use that swear by this steel, and often go on to buy more. They have real skin in the game, their own money, and this speaks more than any other type of evaluation. They have given me the freedom and resources to continue this wonderful journey, and I am eternally grateful for their business, dedication, and support!

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"Gemini" liner lock folding knife, obverse side view. Hollow ground blade is mirror polished 440C stainless steel, thumbnail stud is 304 stainless steel set with 2mm faceted blue sapphires
Mirror polished 440C blade on this folding knife, "Gemini"

440C is here to stay

Collectors, investors, professional knife users, active duty military, and others will continue to specifically order fine custom handmade knives made of 440C (and other steels) based on their needs, desires, and intelligent research. 440C is a fine steel for hand knives, it's bright, beautiful, durable, and proven, when properly processed and finished. It excels in corrosion resistance, and is many times stronger than carbon steels, while being reasonably priced. It has high wear resistance, high toughness, and extremely high finish value, which is seldom mentioned, yet extremely important. It won't soon be replaced in the industrial and military complex as a fine, high grade martensitic stainless steel, and the machine tool industry will continue to rely upon it. There is no current replacement for 440C that has the same characteristics as this steel; if there were, and it was less expensive, it would disappear. This is how all products and their production works.

In knives, there are only a couple steels that can compare with its beauty while exhibiting the toughness and wear resistance that 440C has. A polished 440C blade will hold its finish for many decades with a minimum of care. It's reasonable to sharpen, it's affordably priced and machined. This is why it simply is a popular knife steel and will remain so.

Feel free to enjoy the many 440C blade projects I've made in my three decades of knifemaking on this website, as well as the projects made with other steels! Thanks for being here.

For more information, link to my Heat Treating and Cryogenic Treatment of Knife Blades page.

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"Desert Wind" Persian dagger in mirror finished 440C stainless steel blade, hand-engraved 304 stainless steel bolsters, Mossy Nephrite Jade gemstone handle, Wenge, Cocobolo, Purpleheart hardwood sheath with hand-engraved 304 stainless steel chape
The longevity and beauty of 440C high chromium martensitic stainless steel on this "Desert Wind"

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