Jay Fisher - World Class Knifemaker
Quality Without Compromise
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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) :
These basic elements (along with iron) are a simple combination that works well together, and has for decades.
There is a distinctive steel class, loosely identified as Chrome/Moly. This steel has a reputation for extreme toughness and durability with elevated hardness. These steels are in the 41XX SAE grade, and are used in race car and bicycle frames, aircraft tubing and even rifle barrels. But even these great steels pale in comparison to ATS-34. While 41XX series steels contain some chromium, it is not even close to the amount in ATS-34. The same can be said for the carbon and also the molybdenum. While the reputation for the chrome/moly steels is well deserved, ATS-34 could be described as chrome/moly evolved and refined to tool grade status, or chrome/moly on super-steroids. Here's a chart that illustrates this.
|Critical Alloy comparison between Chrome/Moly and ATS-34 Steels (in percent)|
I left out the less critical alloys to illustrate the profound differences in these steels. While the two steels both have elevated levels of chromium and molybdenum, they are totally in separate genres. The reason I made this comparison is because it's easier to see those differences to give the layman a more generalized understanding of the superiority of tool grade stainless steels and more commonly known and respected chrome/moly steels. Pretty impressive, I think!
For more information, link to my Heat Treating and Cryogenic Treatment of Knife Blades page.
Some history: From my research and experience, ATS-34 is a Japanese version of 154CM, a high chromium, high molybdenum stainless tool steel. The company actually lists this metal as ATS34 (without the dash). It's hard to find an actual reference detailing the origin of both of these steels. Like most knifemakers, I heard through anecdotal details that 154CM (and ATS-34) was developed for jet engine turbine blades, but I can't find a verifiable source for this. 154CM had been around a while when I started making knives, and it's not an actual steel designation, but a trade name.
Why do I mention 154CM? That's because, in nearly every respect 154CM and ATS-34 are the same steel; they have the same alloy contents in virtually the same amounts. A problem arose in the 1980s, when guys like Bob Loveless were using 154CM and touting its wonderful properties; steel mills in the U.S. making the stuff were evidently dropping their quality controls. There was a lot of movement in the steel industry at the time, and mills were closing all over the country. Whatever the reason, we American knifemakers started finding pits, voids, inclusions, and spots in these 154CM steel bars. A knifemaker cannot tolerate the slightest pinhole in a blade, even if he didn't pour the steel and it's not his fault; a knife with a hole or dark spot on the stainless steel blade just won't sell. So knifemakers in those days talked about 154CM and how bad it was getting, when we found out that the Japanese were making ATS-34, their version of this great steel, and the bars and stock were much cleaner, with no voids, holes, inclusions, or debris in the billets. We all heard stories of their quality controls, double pouring, in vacuum furnaces, and high purity environments. So in the 1980s, most of the makers moved to ATS-34. I've read a lot of confusing stories about this movement and direction of steel sources on the internet, and there is a lot of confusing misinformation about the origin of both of these steels. No matter; this is how it played out for me (and a lot of other knifemakers) in the 1980s. We found spots, holes, and inclusions in 154CM blades, could not sell them, and moved to ATS-34 because it was cleaner. Technically, they are the same steel, with only very minor differences in alloy content.
Post-1980s: 154CM made a reappearance, mainly by Crucible Industries. In 2006, they developed CPM154CM, a particle metallurgy tool steel, made by the powder fusing process. This is a fantastic steel, deserving of its own recognition, but it is not the 154CM of the past that was poured in traditional method. The difference is simply the CPM (Crucible Particle Metallurgy) designation. This designation means the steel was sprayed (particles) into a non-segregated mass and pressure forged. More on CPM154CM on its own page.
ATS-34 is a fantastic steel, and because it's been around a while, it's not as intriguing as the newest, latest, pop steel alloy. Do not sell this steel short; it is one of the finest knife blade steels made, with some great properties that are unique and valuable. A very simplified way to understand this steel is to compare it with 440C (featured on this page). You might consider that these steels are essentially the same, except 3-4 percentage points of chromium have been replaced by molybdenum. That's pretty much the difference. What this yields is a tool steel that has somewhat less corrosion resistance than 440C, and reduced chromium carbides, but has markedly greater toughness. Toughness is resistance to breakage or fracture, and this is important to consider in very thin blades, blades that will be under high lateral stress, impact, or are of great length where toughness is key to reduce the possibility of fracture. The chart below will help define this relationship.
To understand this balance between chromium and molybdenum, see this simplified scale:
|Wear Resistance and Toughness in Chromium Steels|
|Alloy Amount||Alloy Content||Beneficial Effect||Limitation|
|⇑ Chromium||High Chromium, Low Molybdenum||Higher corrosion resistance||Lower toughness|
|Balance||Chromium and Molybdenum in balance||Balanced for particular use||Good combination of corrosion resistance and toughness|
|⇑ Molybdenum||High Molybdenum, Low Chromium||Higher toughness||Lower corrosion resistance|
Note that in this chart, unlike the chart on the page dedicated to 440C, carbon has been left out of this comparison. I did this because the carbon content in both 440C and ATS-34 is about the same. The difference in these two steels is the chromium-molybdenum balance. ATS-34 sacrifices the benefits of chromium (mainly higher corrosion resistance) to add molybdenum, which gives it a markedly greater toughness.
The choice of 440C vs. ATS-34 then becomes one of exposure and use. For instance, in my professional tactical combat knives, if marine and jungle environments are to be expected, 440C is usually chosen because it is simply more corrosion resistant than ATS-34. If extreme use and toughness is expected, ATS-34 is chosen. It also depends on the knife geometry and grind. If very thin areas exist on the blade, components, or features, ATS-34 may be a better choice; it's less likely to break under severe mechanical stress in thin cross-sectional areas simply because it's tougher.
ATS-34 is very tough.
An added feature and benefit of ATS-34 steel is that it has very high heat resistance. This steel is tempered (for most uses) at or above 1000°F (538°C). It actually has several ranges of tempering, and most knifemakers temper at the lower range. I've found through my own experience that ATS-34 is much more stable, tougher, and more wear resistant when tempered at the higher range. It also seems stiffer. This would be represented in the modulus of elasticity, which, in my processing experience, is lower at a higher temperature. So I see a totally different character in this steel depending on how it's processed.
The high tempering temperature is markedly different from most other knife steels, which have a relatively low tempering temperature. This means that in order to affect a change the actual hardness, toughness, and temper of the blade, the blade steel in use would have to be heated to above 1000°F! This is very hot, and it's extremely unlikely that the steel would encounter that temperature during most uses. So, even short exposure to a fire won't change the temper of this steel. Also, when sharpening, motor-driven sharpening tools (wheels, buffs, abrasive) would have to bring the edge up to above this temperature to affect the temper. So the steel is very temperature-stable.
The inclusion of chromium at more than 12% means ATS-34 is a true stainless steel. ATS-34 polishes and finishes beautifully. While there is always a grain in the metal, it is comparable to 440C. The grain may have interesting patterns and flow banding when polished, which does not effect the value of the knife. A bit of orange peel granularity can sometimes occur, similar to D2. A high polish in ATS-34 improves its corrosion resistance overall. Unlike many of the more wear-resistant knife steels, ATS-34 holds the high finish indefinitely with little care. In fine art pieces, ATS-34 can be engraved, and the imagery stands out well against a mirror polished blade. Like most of the finer cutlery steels, ATS-34 can be difficult for the knifemaker to polish, taking many steps to achieve a brilliant luster, but it's worth the effort. It's also ridiculously hard to engrave, and most engravers won't touch it. I do, and I like the results.
Like 440C, ATS-34 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. These (and many others) are not new steels, and thus, they are not as pop-exciting as some of the newer alloys.
Are there other good alloys? Of course there are, and some of them have marked advantages over ATS-34. 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 ATS-34, is much more expensive and limited in available sizes. CPMS35VN is tougher, but it can't be mirror polished, has a lower tempering temperature, is very expensive, and limited in available sizes. You won't see this on their data sheets. 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. 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. 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 finishing as a benefit. Finishing is the ability for a knife blade to be polished to a high, even mirror luster. This is critical in art pieces and investment grade knives, and also critical to keep the highest corrosion resistance possible. A rough blade corrodes easier, simply because of increased surface area. More on that topic here.
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.
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.
There simply is no ultimate steel for knife blades: no superior, magnificent, ultimate blade material. Please understand this: If there were a steel superior to all other exotic metals, 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?
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!
Most knifemakers and manufacturers who overly hype their steel type produce an inferior product.
ATS-34 is a long regarded, well-applied tool steel, and it has many applications in the industrial and military field. Just as with 440C, ATS-34 is not a new star, a rising gimmick, or a catchy pop steel. It is a very tough steel, reliable, finishes well, and wears durably in the fields of combat and utility, while having the beauty to take its place in the collector's sculptural knife world. Many of the best knifemakers in the world use or have used this fine steel. So why don't you see it more often used?
Processing Controls: Just as with 440C, this steel can be badly handled during the essential stages of making a knife blade, and any errors here can result in a botched result. This usually shows as a knife that is more brittle than acceptable or more soft than intended for use. While many of the new makers are sending high alloy martensitic stainless steels out to be processed, who is assuring that the absolute critical and distinctive controls of the process are being accomplished?
I know of one instance where a maker found out that his ATS-34 blades were being processed in a batch of 440C blades. This was done because the heat treater simply did not have enough of the ATS-34 blades to fill out his batch, so he just stuck the two types together, and processed for the 440C. This is essential to understand: these steels do not process the same, ATS-34 has a distinctively higher critical temperature, and different quenching process than 440C. So the performance of the ATS-34 was markedly degraded. My own experience has determined that an interrupted fast quench yields a much higher initial hardness on this steel; the same process on 440C would ruin it. Additionally, the higher tempering set is not something most makers (and heat treaters) are doing. This is not just my opinion; I've discussed this with engineers and suppliers of this steel and they all have the same opinion: ATS-34 is a fantastic steel when processed correctly.
Finish value is rarely discussed by novice or unskilled or non-professional knife makers and is never discussed by any factory, because many makers (and all manufacturers) 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 ATS-34 has less chromium than many other steels, a high finish is critical for a knife that is not combat grade or non-reflective. 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.
The reason some of my ATS-34 blades are not mirror polished is simple:
You'll see that the collaborative works on this website with new makers who 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 these new 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 ATS-34 on corrosion resistance particularly since it has less chromium.
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. Here's my take on this:
Heat treat each piece of ATS-34 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 ATS-34 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 ATS-34. 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.
There are people in this field who simply mimic what they have heard. I've seen this for decades in this career field. This site and the book I'm writing are my attempt to clarify what has been misrepresented as fact by the uneducated or inexperienced.
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 of manufactured items that this does not exist, like jewelry, screwdrivers, headstones, 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. If they really want a knife, why not buy one, like everyone else who wants one? It's because they only want it if it is free. How much dedication is that?
The mimics are often people who publicly post their misinformation. 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. They 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!
ATS-34 has been around a while, and will continue to be a top choice in knife performance. It has some very distinctive traits: high toughness, good corrosion resistance, high polish potential, and high temperature resistance that are not quite matched by other knife blade steels. This, coupled with a good array of available sizes and thicknesses, moderate pricing, and the steel's beautiful and flaw-free uniformity will make certain that this steel will always be valued by combat and working knife professionals and high art collectors.
In knives, there are only a few steels that can compare with its tough beauty while exhibiting the high wear resistance and high temperature resistance. I consider it one of my most dependable, reliable, and durable performers, and that is why it will continue to hold its own in my professional studio.
For more information, link to my Heat Treating and Cryogenic Treatment of Knife Blades page.
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