I find these descriptions to be unique and insightful, worth reading by anyone interested in knife steels.
52100 is a high carbon steel used primarily for ball bearings. It has a good amount of carbon (0.98 - 1.10) and very few other alloys. Ball bearing steels usually have to withstand a great deal of force in a very small area. Traditionally, ball bearing steels make good edge steels because an edge also has to withstand much force in a small area. 52100 serves that function well.
Oil quenched and drawn to Rc 62, it is a difficult steel to heat treat. A very fine molecular structure permits very sharp edges, even at thin angles. Toughness is good, corrosion resistance isn't. It is not a stainless steel and will have to be cared for.
My comments here. I missed this early mule, but this is a very interesting steel. As a ball bearing steel it is a very refined carbon steel. It will rust easily, but this has not been an issue for me (I now have the PM2 in 52100). The following are some comments by EvilD on the Spyderco forums:
Something I've noted in using and sharpening mine is what I like to call "repeatable results". Any steel I've owned and used, I can get to my desired sharpness eventually and one way or another. Some of them are more finicky than others and need more attention and your technique needs to be spot on. With this steel, I've had the easiest time getting repeatable sharpness every time on the Sharpmaker. I have yet to reach a point where I've struggled to get it to that level of sharpeness I'm looking for.Maybe something of note, is that for whatever reason I can't seem to reach that level with just the brown stones. Someone here mentioned in the first 52100 discussion thread, in so many words, that people would need to brush up on their sharpening techniques and really work to get this steel sharp because you won't have carbides to rely on for cutting ability. This makes sense, because to get it as sharp as I want it, I have to use the white rods every time. I can get it very sharp on the browns, sharp enough to slice any type of paper and shave, but when I put it on the fine and then super fine rods it kicks it way up into the "tree topping hairs" sharpness where it will catch and cut free hanging hairs without touching your skin at all.
There definitely seems to be a difference between 52100 and something like the S##V steels that perform well with ~400-600 grit edges. This steel seems to really excel at higher polish edges and I would suspect that anyone who takes the time to polish the edge up to a mirror finish will be rewarded with a ridiculously sharp edge. I haven't put mine on the Edge Pro yet but when I do I'll be polishing the edge for sure.
Another note for those interested is that I haven't stropped this knife one time. I'm not into the idea of maintaining an edge with just a strop, and it's so sharp coming off the super fine rods that I haven't bothered even trying to see what a couple passes on leather will do. Before I take it to the Edge Pro I'll probably play around with some diamond paste and see how that goes.
MT04P ZDP-189 Mule was originally released in a very limited quantity due to unforeseen issues. The Mule Team project was created to give more people access to various steels using a standard pattern for a fixed blade knife. The hope of the project was to find out what these steels can do by making them available at an affordable price for our Knife Knuts and Steel Junkies. We test our products constantly, but we’ve always maintained that no amount of “testing” can provide the information that real-world use can.
With the ZDP-189 Mule our goal was to reach the optimal hardness that we had in our folders (in 2009 as well as presently). Shortly after the release of MT04P it was discovered that the optimal hardness is different for a fixed blade. Once this was discovered Spyderco placed a hold on shipping any additional MT04P Mules.
The Mule Team is a project based upon the desire to learn more about different types of steel and the performance of each steel. The scenario with the MT04P Mule, although not planned, certainly provided some previously unknown and valuable information into one of our industry’s most exotic steels.
9Cr18Mo is a premium ingot high-carbon steel. In our experience it's the best knife steel being produced in China today. The name is derived from its component elements: .9% carbon, 18% chromium and 1% molybdenum. With controlled heat treat and tempering it reaches a HRc of 58-62. Before its entry into the knife industry it was widely used for high-end Chinese barbering scissors, roller bearings and surgical tools due to its corrosion resistance and high processing quality. The application of 9Cr18Mo to knife manufacturing opens up another steel option for high-end knife manufacturers and their high-end knife enthusiasts alike. The addition of a 9Cr18Mo Spyderco Mule fleshes out the series further by offering users the opportunity to evaluate and test drive a high-performance steel from yet another country.
Crucible Steel in NY created CPM S30V as steel developed specifically to be used for knife blades. A first, and the knife industry appreciates such purpose built efforts.
Shortly after the introduction of CPM S30V, Chris Reeve (of Chris Reeve Knives) began working with Dick Barber, a metallurgist at Crucible Steel (at the time). The goal was to create an even better version of the steel that had better machinability and finish. After several years of testing and development, the result was CPM S35VN. Chemically the same as S30V, but with the additional of Niobium (also referred to as Columbium).
High Chromium ferritic steels containing Niobium exhibit increased temperature stability and refined grain structure which is important when working hard steels used in items like jet and rocket engines, welding and knife blades. It increases a blade's strength and ability to take and retain sharpness.
Crucible worked with a few makers to test and refine the steel. Production began on CPM S35VN just before changes were made in the Crucible business model. At this time, there is still question as to whether this fine steel will be in production. Spyderco was fortunate to be able to grab some while it was still available and this Mule Team model is the result of that opportunity.
CPM S35VN is exotic in its chemistry, even for powdered steels. This is an opportunity for some to be able to play with this new evolution to blade steel.
(The general word is that this is virtually indistinguishable from S30V for the end user, but is somewhat easier to machine for the knife maker.)
Knife and steel-devotees love trying out new blade steels. Spyderco leads the industry in offering, testing and manufacturing knives using new and exotic blade steels. Taking that idea a step up, why not offer a series (team) of blades using different, exotic and freshly unveiled steels? In doing this steel-obsessed knife knuts can try, test and use something normally not offered to the industry.
Spyderco's Damascus Mule Team is a laminated fifteen-layer steel with a Suminagashi pattern. The Damascus Mule's steel is composed of layers of erosive and non-erosive material over a VG-10 core center. The erosive layers are hard martensite stainless steel and the non-erosive layers are anti-corrosion nonferrous metal. These layers block carbon particles in the core from spreading to the outer layers. After layering the blade is forged to intentionally distort the layer-lines making a complicated, artistically beautiful pattern called Suminagashi. Suminagashi is the traditional Japanese art form of creating ripples of Chinese ink on the surface of water. This steel mimics the art form with interesting results on a knife blade. Once the layers are distorted, the blade is bathed in acid, etching the pattern to vivid relief.
CTS BD1 is patterned on Gingami I (also known as G2), the gold-standard for Japanese cutlerers. Its superior edge retention and surface finish are machined to a fine edge and it heat-treats consistently. From a performance standpoint, it's a winner and it's used in Spyderco's latest Mule Team fixed blade. The CTS BD1 Mule is a limited 500-piece run with a sharpened PlainEdge cutting edge.
Upstate New York's Crucible Steel manufacturers Cru-Wear which is very similar to Vascowear, a steel used by Gerber Legendary Blades in many of their past production knives.
Cru-Wear is a high-performance "V" tool steel that is difficult to process making it challenging for knife manufacturers to work with. It follows the same high-alloy, metallurgical tool-steel recipe used to produce D2, but with greater levels of vanadium, tungsten, and molybdenum. It is air-hardened and worked in a cold state. Cru-Wear exhibits exceptional toughness, impact resistance, and hardness for exceptional edge retention and is the first tool steel offering in Spyderco's Mule Team Series.
Böhler first sold steel in North America in 1925 by providing European-made steels to toolmakers, manufacturing industries and construction jobs in the U.S. Their Elmax is an alloy composed using powdered metallurgic technology that was designed specifically for high-tech applications, primarily for use in the electronics industry. It contains elevated levels of chromium, vanadium-molybdenum that deem it a well-tailored fit for making knife blades. These elements translate into resistance to wear and corrosion and it has a homogenous grain structure making it malleable when grinding and forming.
Carpenter’s CTS B75P is comparable in elemental composition to BG42 blade steel but is produced using a powdered steel manufacturing process rather cast steel construction. Powdered steel manufacturing renders the ingredients and carbides making up the steel’s structure more consistent in grain size to each other and homogenize the steel. For the knife user this translates into a high-performance knife steel with exceptional wear and corrosion resistance and long term edge retention. CTS B75P’s hard vanadium carbides further augment its wear resistance and edge retention making it the new knife steel that production knife companies and custom knifemakers are excited to use.
The Carpenter MT15 CTS B75P Mule is a limited-piece run with a sharpened PlainEdge cutting edge.
CTS XHP is air hardened, high carbon, high chromium, corrosion resistant blade steel. It exhibits exceptional hardness similar to that found in tool steels such as D2, but also offers corrosion resistance on par with high chromium stainless steels like Type-440C.
The powdered steel manufacturing process renders the steel’s ingredients and its carbides with a more consistent grain size. When grains are similar sized, the result is a more homogenized steel structure. For the person cutting with the blade this translates into higher-performing knife steel that has exceptional wear and corrosion resistance and long lasting edge retention. CTS XHP contains hard vanadium carbides further augmenting its hardness level to produce a keenly sharp cutting edge and surface finish. Even exposed to moisture, petroleum products and organic materials it exhibits exceptional corrosion resistance.
K390 is a powdered metallurgy, cold work tool steel with 9% vanadium and added tungsten and cobalt for excellent wear resistance and high compressive strength that is a workhorse in even the most severe applications.
The carbides in the K390 mix are fine in texture and the steel’s remaining components are uniformly sized and distributed evenly throughout the matrix. This equal distribution of elements adds to the overall strength and cutting capacity when the blade is finished and sharpened.
What differentiates CPM S110V from other blade steels is its volume of vanadium-rich (9.0%) and niobium-rich (3.0%) alloys which classify it as a martensitic stainless tool steel. Crucible’s powdered metal process creates uniform carbide distribution of the steel’s components throughout the blade for superior wear resistance, toughness and corrosion protection. These are positive performance characteristics highly desired in state-of-the-art exotic blade steels.
PSF27 combines the advantages of the Spray Forming Process with an alloy composition (1.55% carbon, 12.00% chromium, 0.75% molybdenum, 1.00% vanadium) that is basically equivalent to D2 tool steel. The synergy of these alloys and the Spray Forming Process results in a steel that offers increased toughness, wear resistance, crack resistance, and higher hardness. It is also more predictable and dimensionally stable during the heat-treatment process.
CTS B70P is a powder metallurgy derivative of Carpenter’s CRB-7 alloy, but offers improved wear resistance and hardness capability. Its corrosion resistance is very comparable to 440C stainless steel. Collectively, these qualities make it an excellent candidate for cutlery applications.
Like conventional steels, particle metallurgy steels begin with a homogenous bath of molten high-alloy steel. However, instead of being poured into ingot molds, the molten steel is forced through a nozzle under high pressure to create a spray of small spherical droplets that quickly solidify into powder particles. The small size of the particles forms micro-ingots, drastically reducing the alloy segregation in the steel and ensuring an extremely fine, uniform carbide structure. This enhances the steel’s edge retention, as well as its grinding and polishing characteristics.
CPM 4V's exact alloy composition is as follows: Carbon: 1.35%, Manganese: 0.40%, Silicon: 0.80%, Chromium: 5.0%, Molybdenum: 2.95%, Vanadium: 3.85%.
Spyderco’s twenty-second Mule Team installment features RWL 34, a "rapidly solidified powder" (RSP) martensitic stainless steel made by the renowned Swedish firm Damasteel®. RWL 34 is a variation of the 420 martensitic stainless family that contains 14% chromium, as well as molybdenum and vanadium for improved corrosion resistance, hardness, and strength. The performance of these alloys is further enhanced by the RSP process, which involves using high-pressure nitrogen gas to force the molten steel through a nozzle. Just as in the CPM process used by Crucible, this creates a spray of small spherical droplets that rapidly solidify into powder particles, drastically reducing the segregation, or settling, of the alloys in the steel to produce an extremely fine, uniform carbide structure.
RWL 34 has long been a favorite of custom knifemakers—particularly Canadian maker Brian Tighe, designer of the Tighe Stick—because of its high-performance characteristics and the fact that it is capable of taking an extremely high polish. However, it has not been used in the production of factory-made knives because it was not available in large sheets. Recent improvements in the availability of the material have changed that situation, so Spyderco quickly seized the opportunity to incorporate RWL 34 into our Mule Team Project.
RWL 34's alloy composition is as follows: Carbon - 1.05%, Manganese - 0.50%, Silicon - 0.50%, Chromium - 14.0%, Molybdenum - 4.00%, Vanadium - 0.20%. This advanced alloy mix makes it a very close equivalent of 154 CM and ATS-34 stainless steels, but since it has the additional advantages offered by the RSP process, it is actually closest to CPM 154—Crucible’s particle metallurgy version of 154 CM — with the addition of several trace elements.
Spyderco's twenty-third Mule Team installment features CPM 20CV steel, a highly wear resistant, powder metallurgy stainless tool steel. CPM 20CV is unique in that it contains a high volume of vanadium carbides and the highest amount of chromium of any high-vanadium stainless steel currently available. This potent combination of elements gives it a remarkable combination of high wear resistance, superior corrosion resistance, good impact toughness, and excellent polishability. These properties are maximized by the powder metallurgy process, which ensures an extremely clean steel with small carbides and a very fine grain size.
CPM 20CV excels in industrial applications that demand high wear resistance and high corrosion resistance, such as plastic injection feed screws, barrel liners, screw tips, and mold cavities. It is also used in food processing equipment and pelletizer knives and is an extremely popular blade steel in high-performance custom knives.
CPM 20CV's alloy composition is as follows: Carbon: 1.90%, Manganese: 0.30%, Silicon: 0.30%, Chromium: 20.0%, Tungsten: 0.60%, Molybdenum: 1.00%, and Vanadium: 4.00%. An advanced alloy that offers outstanding potential in high-performance cutlery applications, CPM 20CV is a truly unique blade material and we are proud to feature it on the MT23 Mule Team blade.
Maxamet\'s remarkable alloy composition includes: Carbon: 2.15%, Manganese: 0.30%, Sulfur: 0.070%, Silicon: 0.25%, Chromium: 4.75%, Cobalt: 10.00%, Vanadium: 6.00%, and Tungsten: 13.00%. This sophisticated mix of elements, combined with the advantages of powdered metal technology, give it an extraordinary balance of wear resistance and toughness at high hardness levels.
Spyderco’s twenty-fifth Mule Team installment features LC200N steel - a high nitrogen alloyed tool steel that offers extreme corrosion resistance. LC200N is produced by a combination of the PESR (Pressurized Electric Slag Remelting) process and “smart forging” technology to yield an amazing increase in the steel’s purity and a very fine and homogenous microstructure. It is also a true martensitic steel that achieves its hardness through traditional heat treating, so its hardness level can be precisely controlled to meet the demands of specific uses. Regarded as the material of choice for applications that involve high static and dynamic loads in corrosive environments, LC200N is widely used in the food, chemical, recycling, and pharmaceutical industries, as well as in mirror-polished dies used in the plastics industry. It is best known, however, as NASA’s preferred material for the ball bearings used in their aerospace equipment.
LC200N’s unique alloy composition includes: 0.3% Carbon, 15% Chromium, 0.5% Nitrogen, 0.95% Molybdenum, 0.5% Nickel, and 1.00% Manganese. When this alloy recipe is translated to knife blades, LC200N provides an exceptional blend of toughness, edge holding, and corrosion resistance.
Spyderco’s twenty-sixth Mule Team installment features Carpenter® Technology Corporation's Micro-Melt® A11, a particle metallurgy version of A11 tool steel. Also known as AISI A11, K294 (Böhler-Uddeholm), CPM® 10V (Crucible®), and PMA11. It is an extremely wear-resistant tool steel that is capable of achieving a high working hardness. One of the world's premier steel choices for highly wear-resistant industrial tooling, in its CPM 10V form it is also one of the favorite steels of renowned custom knifemaker and Spyderco collaborator Phil Wilson.
PMA11's alloy composition is as follows: Carbon: 2.45%, Manganese: 0.50%, Silicon: 0.90%, Chromium: 5.30%, Molybdenum: 1.30%, Vanadium: 9.50%, Sulfur 0.08%. Its large volume of hard vanadium carbides provides substantially better wear-resistance than typical high-carbon, high-chromium die steels such as D2 and D7. In knife blades, this translates to outstanding edge retention and good toughness, especially in shorter knives. These properties are maximized through the particle metallurgy process, which greatly reduces alloy segregation and ensures a homogenous microstructure. Please note, however, that PMA11 is a tool steel and must be maintained properly to safeguard it against corrosion. PMA11 is an advanced alloy that offers excellent potential in high-performance cutlery applications.
Spyderco’s twenty-seventh Mule Team installment features Carpenter® steel's Micro-Melt® PD#1 alloy, an air-hardening cold-work die steel. PD#1's unique alloy composition gives it wear resistance significantly superior to conventional steels like D2, while still maintaining excellent toughness. Thanks to Carpenter's advanced Micro-Melt powder metallurgy process, PD#1 possesses an extremely fine microstructure and uniform carbide distribution, as well as the enhanced compressive strength necessary for the demands of tooling applications. Collectively, these qualities give it a unique combination of wear resistance and toughness that make it ideal for use as a blade steel.
PD#1's unique alloy composition includes: 1.1% Carbon, 7.75% Chromium, 1.2% Silicon, 1.6% Molybdenum, 1.1% Tungsten, 0.25% Manganese, and 2.35% Vanadium. Note that its moderate Chromium content provides only limited corrosion resistance, so please maintain your knife properly.
Note that "27" is the atomic number for cobalt. It was said that the initial inspiration for this steel was to make a domestic version of VG10, but if you look at the composition you will see that they have gone significantly beyond that.
Expertly crafted from our new, proprietary blade steel, CPM SPY27, the MT28 Mule Team is a fully sharpened fixed-blade blank that allows knife enthusiasts and hobbyists to attach their own handle scales and conduct their own performance testing.
In close cooperation with Crucible® Industries, we have developed CPM SPY27, a particle metallurgy stainless steel containing a proprietary mix of alloys, including vanadium, molybdenum, niobium, nitrogen, and cobalt. This remarkable composition, enhanced by the amplifying effects of cobalt and the state-of-the-art Crucible Particle Metallurgy process, is produced exclusively for Spyderco.
The latest addition to this elite family features Z-Max PM, an ultra-high-performance powder metallurgy tool steel enriched with vanadium, tungsten, molybdenum, cobalt, and two percent carbon. Capable of being heat treated to extreme hardness, it offers exceptional wear resistance and edge holding properties.
Z-Max is almost identical to CPM Rex 121, which is a very exotic steel. It has a huge amount of carbides and can be heat treated to 68HRC. It is closer to Maxamet than any other knife steel. It is extremely hard, with tremendous edge holding, but sacrifices toughness. It can be hardened even beyond HRC 68, but that will sacrifice even more toughness.
This addition to Spyderco's popular Mule Team series showcases Z-Wear PM -- a particle metallurgy cold work tool steel produced in Germany by Zapp. Created to tackle the most demanding industrial applications, it offers wear resistance superior to A2 and D2 tool steels while providing increased toughness and resistance to chipping.
When Crucible Industries created CPM S35VN for the cutlery industry, they formulated it to provide increased toughness over CPM S30V while maintaining the same level of edge retention. CPM S45VN takes that development a step further, adding Niobium and Nitrogen in place of some Vanadium and Carbon to provide a more finely tuned balance of edge retention, wear resistance, and corrosion resistance.
Tom's Knife Info / tom@mmto.org