Knife Steel Types

STEEL TYPES

http://www.zknives.com/knives/steels/steelchart.php

C = Carbon,   Cr = Chromium,   Mo = Molybdenum,   W = Tungsten,   V = Vanadium,   Mn = Manganese,  

Si = Silicon,   Co = Cobalt,   S = Sulfur,   P = Phosphorus,   Nb = Niobium,   Cu = Copper,   Ni = Nickel 

M398 (Bohler-Uddeholm) - Bohler-Uddeholm introduced M398 steel in 2019. At least that's when it appeared on various knife related forums. M398 is intended as an evolution and improvement over a well known Bohler-Uddeholm M390 steel. As far as pure wear resistance is concerned, it definitely is an improvement. M398 has a lot more Carbon, 0.70% more of it, and 3.2% more Vanadium -making it whooping 7.20%. Obviously, this isn't a steel which is easy to work with, M390 steel wasn't an easy one to begin with. From what I've gathered so far, forging is theoretically possible but very difficult, only at low temperatures, with low strength impacts. Other than that, it's a very high carbide volume steel, 30% to be precise, for comparison, it's predecessor - Bohler-Uddeholm M390 steel had only(!) 20% carbide volume. In the end, both, working hardness and wear resistance have been increased, sacrificing toughness in process. I've seen a few M398 knives already, one of them in 66-67HRC range, which is pretty impressive. I'd be interested to get my hands on one of those. I'd guess neither sharpening, nor finishing the blade will be an easy task. Based on the characteristics, M398 is better suited for smaller, high performance cutters, and I'd also assume that this isn't the steel suited for high polished, acute edges, just like many other high carbide volume, highly alloyed steels.

M390 (Bohler-Uddeholm) - Bohler-Uddeholm martensitic Chromium steel, made using their 3rd generation PM process. M390 features very high wear and corrosion resistance. Fine grained alloy, popular choice for high end folders and small fixed blades. working hardness up to 62HRC. Excellent performance with both, coarse and high polished edges. You still need about 15° per side edge to get the best performance and edge holding. Thinner than that, and you will run into the issue with the thin edge not being able to support all those carbides to make the edge perform. Working hardness can reach 62HRC, and most of the production knives I've seen are in 60-62HRC range. Overall, it is of the best performers as far as corrosion and wear resistance go, and because of that it is a popular choice for high end, and the limited edition knives. Aside from very good edge holding ability, maintaining the edge is very easy. And one more thing worth noticing, there's no stubborn burr forming during sharpening, therefore, there's no risk to form a wire edge either.

Damascus Steel production is a continuation of the ancient and best blacksmithing traditions of past centuries. Damascus steel story is entangled in many secrets and mysteries, transmitted from master to master. Damascus steel blades brought from the East, Europeans saw for the first time in the 19th century.  Since then, many types of this layered metal have been mastered in Russia.  The essence of Damascus manufacturing technology lies in the forging of various grades of steel with different carbon contents. Manipulations with the number of welded layers of steel and their relative location in the mass of metal determine the pattern on the surface of the blade and create the effect of a mechanical micro saw on the cutting edge.  As a result, the blade has up to 1,500 layers of steel. After heat treatment, the blade has a hardness of 60 HRC, so it has excellent cutting properties. According to professional hunters, a well-sharpened knife can be used to skin and process a moose without much effort without additional sharpening of the cutting edge. Moreover, this steel will cut with ease various food products and all types of wood.  Thanks to well-executed tempering after hardening, the blade also has elastic deformation, which allows its brittleness under mechanical stress to be minimized. At the final stage, before sharpening, the knife blade is etched in an acid solution to emphasize its individuality.

Wootz Steel is a composite material based on ledeburite steel (chromium content of at least 12%, carbon content of at least 1.5%) with a pronounced heterogeneous (heterogeneous) structure, realized in the material through high-temperature (750-1050 ° C) multiple thermal cycling followed by slow cooling at a rate of not more than 0.3-0.5 ° C / min. The volumetric content of the carbide component is at least 25%. After the forging operation, carbide inserts line up along the forging lines, providing volume reinforcement of the product with a high-hard (carbide) component of the material, which makes it possible to realize a “ripping” effect and a self-sharpening mechanism on the cutting edge of the product. Alternating carbide precipitates with carbon depleted zones provides significant impact resistance to the cutting edge. Products made from this composite material are characterized by a long working life of the cutting edge and easy recoverability of the cutting properties when using ceramic musat and other sharpening abrasive devices. Wootz steel blades are characterized by high anticorrosion properties and have a hardness of 61-62 HRC. They are sharpened by using ceramic musat, diamond and other sharpening, abrasive devices.

Laminate Steel blade or piled steel is a knife, sword, or other tool blade made out of layers of differing types of steel, rather than a single homogeneous alloy. The earliest steel blades were laminated out of necessity, due to the early bloomery method of smelting iron, which made production of steel expensive and inconsistent. Laminated steel offered both a way to average out the properties of the steel, as well as a way to restrict high carbon steel to the areas that needed it most. Laminated steel blades are still produced today for specialized applications, where different requirements at different points in the blade are met by use of different alloys, forged together into a single blade.

CPM Rex 121 (Crucible) - Developed in 1998. CPM REX 121 is a high vanadium cobalt high speed tool steel designed to offer a combination of the highest wear resistance, attainable hardness, and red hardness available in a high-speed steel. As far as hardness is concerned, it is truly a champion, capable of reaching 70-72HRC. For the record, officially, Rockwell C scale maxes out at 70. Extremely high wear resistance as well. Difficult to grind and consequently, difficult to sharpen too. Frankly, sharpening this alloy is borderline nightmare even at 68HRC, and it will be exponentially harder at higher hardness. I've killed ceramic belts on the grinder trying to thin down the edge on Rex 121 knife, and even 120 grit DMT wasn't much of a success. With that much alloying elements in it, carbides are abundant, and some of them are not very small either. In the end, it works better with coarse edge, and I am not sure how many people would have a patience to sharpen 100K edge on that thing anyway.

CPM S125V (Crucible) - Developed in 2004. Few years later was discontinued, but then reappeared. Few custom makers in US (Phil Wilson, Farid) and in Italy (Fantoni) use it. CPM S125V has Extremely high wear resistance. As far as I know, it was originally developed for dental industry, however since S125V was too difficult to machine didn't really take off. Edge holding and corrosion resistance are very high. As far as knives are concerned, it works superbly well. Rebeveling can be a problem if one doesn't have proper sharpening equipment and skills. Diamonds and Japanese whet stones work fine though. Definitely not a good choice for novices in sharpening. Edge holding is very high. Due to very high carbide volume and size of the carbides, it works better with coarse edges, around 400-1000 range works best in my experience.

CPM S110V (Crucible) - Relatively new steel from Crucible. Developed in 2005. Very high wear resistance and better corrosion resistance than CPM S125V steel. Interesting part is the addition of the Niobium to the alloy, which forms very hard, very fine carbides. They're harder than Vanadium carbides and form in substantial amounts even at lower hardness. Can get up to 64HRC.

CPM S90V (Crucible) - First introduced in 1999. Very good, highly stain and wear resistant CPM steel from Crucible. Base for this alloy was AISI 420 steel with added Vanadium, really large amount though. I've tried it with high polished, 100k edges and with coarse edges as well, ended up choosing coarse edge, lasts a lot longer, especially on highly abrasive mediums.

CPM S60V (Crucible) - First introduced in 1995. Now discontinued. Highly wear and stain resistant steel. High carbide volume with fine carbides. Not that easy to put a sharp edge on it though. Base for this alloy was AISI 440C steel with added Carbon and Vanadium. Main issue with making knives out of it was low attainable hardness, around 56HRC. Sure, there are knives softer than that too, but for a knife made of super steel it was too much of a trouble.

S390 Microclean (Bohler-Uddeholm) - Bohler-Uddeholm PM steel. High speed, red hot hardness tool steel. Good toughness and wear resistance. Roughly equivalent of AISI T15 high speed tool steel. I'll soon move this alloy into its own group, since S390 Microclean isn't all that close to neither AISI T15 steel nor AISI M3:1Co, to warrant being in the same group. Meanwhile, Kase Knives Switzerland(kase-knives.com) just posted a video (09/23/19) with S390 Microclean testing results, where the thin bladed knife, with 0.02" behind the edge thickness edge managed to cut through the steel nail and brass tube, with no edge damage. The test knife was a very impressive 68HRC. Overall, from what we can see based on published data and Kase Knives tests, S390 Microclean steel can be an extremely high performer, and I suppose based on the heat treatment protocol used it can do very well with both, high performance cutters and, the larger, more heavy duty use knives. Also, worth noting, carbide size is in 3µm-5µm range, which is quite fine compared to many other high alloy steels.

VG10 (Takefu) - High-end stainless steel. VG-10 takes a very good edge and holds it well. Very popular with Japanese kitchen knife makers and with knife makers in general. Typically it is around 60-61 HRC, although some makers take it to 62HRC. Popular choice for kitchen knives, folders, fixed blades, etc. Good edge holding and stain resistance. Works well with high polished, acute edge, but depending in the application acute edge part may need revision. As in, if you plan to use the fixed blade for chopping would be better to beef up that edge a bit.

Vanadis 10 (Bohler-Uddeholm) - Very high alloy, high wear resistance tool steel. As per manufacturer's documentation, very high wear resistance is achieved without significant compromises in toughness. Capable of working hardness between 60-65. Properly heat treated, makes a very good knife blade. I've used Phil Wilson Bird And Trout Knife in Vanadis 10 at 65HRC for few years now, and I have nothing but positive results. Have to go with coarse edges due to very high carbide volume, but thin blade and 15° per side edge make an excellent cutter, which holds the edge for a very long time.

Vanadis 8 (Bohler-Uddeholm) - Based on the official Bohler-Uddeholm documents, Vanadis 8 was conceived as a successor and improvement over earlier Vanadis 10 steel for industrial tooling. Improvements are noticeable in impact strength, dimensional stability and chipping resistance. Abrasive wear resistance is better than that of the Vanadis 10 steel (except for the galling test where Vanadis 10 steel has an edge), for the same reason, machinability and grindability of the Vanadis 8 is lower. As per specifications, working hardness is in the 62-65HRC range, similar to its predecessor. I've seen a few knives made out of the Vanadis 8 steel already, and I suppose more will come, it looks like a very promising steel. Considering that Vanadis 8 steel improves Vanadis 10 steel which is a very good knife steel when properly heat treated, the results should be well above the average. To be exact, I've been using Phil Wilson Vanadis 10 Bird and Trout Knife at 65HRC for years and I have nothing but positive results. Getting something better than that is no easy job.

Elmax (Bohler-Uddeholm) - Uddeholm steel. Often referred as UHB Elmax, although I am not certain where does that come from, definitely not from Uddeholm catalogs. UHB might be Uddeholm-Bohler abbreviation, just a guess. In their color coding this is blue/black code steel. Meaning, Cold Work/High Performance steel. As far as the knives are concerned, interesting properties Elmax's are high wear resistance coupled with its high corrosion resistance. Max working hardness is about 62HRC, although production knives are mostly in 60-61HRC range. Elmax is considered one of the premium alloys for folding and small fixed blade knives. When used with coarse edge about 400-800 grit range it has durable, very aggressive edge, but Elmax can also support very fine, high polished edges as well. For a high carbide, high chromium steel Elmax is still reasonably tough. Doesn't mean it will make a good sword at 62HRC, but as far as folders and small knives are concerned it is one of the top choices. PM process used in making Elmax reduces grain size and helps with carbide distribution, both of which positively affect steel properties necessary for the knife blade. Bohler-Uddeholm M390 steel is quite similar, and a bit better performer then Elmax, although you'd be hard pressed to tell the difference unless you had two identical knives with optimum heat treatment to compare to each other. In real life, knife edge and blade geometry, plus heat treatment protocols would play a bigger role then the differences in their chemistry.

Niolox (Lohmann) - Stain resistant tool steel, with good edge holding and decent toughness. Contains niobium, one of the best carbide former, although there's not a lot of it (Niobium) in the alloy. In knives, typical working hardness range is 58-63HRC. Even without PM technology, it is a very fine-grained steel, which obviously is a positive and aids with edge stability. Strangely, even though it's not an expensive alloy, not very popular with knife makers, mainly used by German, French and Belgian knifemakers. Supposed to have AISI D2 like wear resistance, and better edge stability.

LSS PGK (Latrobe) - Latrobe air hardening, cold work knife and die steel. At 60HRC is should have similar wear resistance with D2, being much tougher. Go figure, why D2 is popular and this one isn't.

D2 (AISI) - First appeared during WW II, semi-stainless tool steel. Very popular even today. Pretty much every steel manufacturer makes it and it's quite popular with knifemakers, custom and factory alike. Composition-wise it's almost a stainless steel. Resists rust pretty well, good edge holding and ok toughness. Bob Dozier is perhaps the most acknowledged expert of D2 steel knives.

N690 (Bohler-Uddeholm) - Bohler-Uddeholm steel, recommended working hardness 58-60HRC. Similar to VG-10. Later, Aichi produced pretty much identical (with N690), ZA-18 steel, promoted to be better a performer than VG-

K390 (Bohler-Uddeholm) - Bohler-Uddeholm PM cold work tool steel. High wear resistance and good toughness.

K340 (Bohler-Uddeholm) - Bohler-Uddeholm cold work steel.

K300 (Bohler-Uddeholm) - High shock and impact resistant steel. Suitable for large, heavy duty knives, and wear resistance isn't too low either.

K110 (Bohler-Uddeholm) - Equivalent of AISI of D2 tool steel.

H12MF (GOST) - Russian equivalent of the AISI D2 tool steel. Unlike standard D2, and most of the versions of it, contains trace amounts of Cu (Copper).

KH12F1 (GOST) - Russian equivalent of the AISI D2 tool steel. Unlike standard D2, and most of the versions of it, contains trace amounts of Cu (Copper).

KHV5 (GOST) - Tool steel with very high working hardness, 67-69HRC. Used in knives by Ukrainian maker Kulbida.