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The hardness of steel is usually stated as a number on the Rockwell C scale (HRC). The Rockwell scale is a hardness scale based on the resistance to indentation of a material, as opposed to other scales such as the Mohs scale (scratch resistance) testing used in mineralogy. As hardness increases, the blade becomes capable of taking and holding a better edge, but is more difficult to sharpen and more brittle (commonly called less "tough"). Laminating a harder steel between a softer one is an expensive process that to some extent gives the benefits of both types.
A6, This grade of tool steel air-hardens at a relatively low temperature (approximately the same temperature as oil-hardening grades) and is dimensionally stable. Therefore it is commonly used for dies, forming tools, and gauges that do not require extreme wear resistance but do need high stability.
A7, (No description available)
A8, C .55% Mn .30% Si .30% Cr 5.00% Mo 1.25% W 1.25%
A9, (No description available)
A10, This grade contains a uniform distribution of graphite particles to increase machinability and provide self-lubricating properties. It is commonly used for gauges, arbors, shears, and punches.
D2, has a high chrome content of 12.00%, it is called "semi-stainless", because of the lack of free Chromium in solution. While not as tough as premium carbon steels, it is much tougher than premium stainless steels.
O1, popular forging steel. Good wear resistance and edge stability. Relatively tough, but not as much as A2 or 5160. It is most commonly used by Randall Knives, Mad Dog Knives, and many other custom knife makers.
M2, slightly tougher than D-2. Capable of keeping a tempered edge at high temperatures. However, it is hardly used anymore in factory production knives, CPM M4 is becoming more popular. Custom knife makers still use it for knives intended for fine cutting with very thin edges.
S1 A Shock-Resistant Medium Carbon Tool Steel which combines moderate hardness with good impact toughness. Carbon content .40 - .55%.
W1, water hardening tool steel.High carbon content.
W2, tool steel, holds edge quite well. Not very tough. Has a carbon content of 1.5. Correction. Most readily avaialble W2 has a carbon content of no more than 1-1.1%. It can be left at high hardness levels (it can attain as quenched hardess of 67 Rc) and still be quit tough especially in larger knives with thicker spines as the core of the thick portion of the blade does not attain full hardness because of the shallow hardening nature of the steel. Bill Moran considered it to be almost a tough as 5160, but it was unavailable for a period of time.
Crucible Material Corporation tool steels produced using CPM process
CPM 1V, proprietary steel, very high toughness, several times higher than A2 with and same level of wear resistance.
CPM 3V, proprietary steel, very high toughness, less than CPM 1V, but more than A2, and high wear resistance, better than CPM 1V. Used by several custom knives makers and factories, including Jerry Hossom, Reese Weiland. Makes good choice for the swords and large knives.
CPM M4 (AISI M4), High speed tool steel produced by Crucible using CPM process. M4 has been around long time, lately entering custom and high end production knives.
CPM 9V, modification of CPM 10V with lower carbon and vanadium to improve toughness and heat check resistance.
CPM 10V (AISI A11), highly wear-resistant tool steel, toughness comparable with D2 tool steel. Currently used by a few custom knife makers. Phil Wilson uses CPM 10V and other CPM steels.
CPM 15V, proprietary, extremely high wear-resistant tool steel, thanks to 14.5% Vanadium content. Found only in custom knives.
Chrome steel is one of a class of non stainless steels which are used for applications such as bearings, tools and drills.
52100, ball bearing steel. In terms of wear resistance, a little better than that of the O1 steel, however 52100 is also tougher. It has very fine carbides, which translates into high edge stability. Used by many custom makers, Swamp Rat knives uses 52100 steel under the name SR101. Also referred to as 100 Cr 6/102 Cr6 as per ISO nomenclature and confrorms to BS grade En31.
SUJ2, a steel that we have no information about except the fact that it exists.
DIN 5401, the fact that it exists.
Steels that did not fit into the stainless category because they may not have enough of a certain element, such as chromium.
V-Gin1, Fine-grained steel with Mo, V for the best effect of Cr.
V-Gin2, More Cr is added for better corrosion resistance.
V-Gin3B, More Cr is added for better corrosion resistance.
Stainless steel is a popular class of material for knife blades because it resists corrosion and is easy to maintain. However, it is not impervious to corrosion or rust. In order for a steel to be considered stainless it must have a chromium content of at least 13%.
The principle of stainless steel is that in an oxidizing chemical environment the oxide (chromium and sometimes nickel and other metal oxides) is stable, and when in a reducing (shortage of oxygen) environment at least one metal is stable. This usually works, except in an acid environment. In order to be hardenable, knife steel can contain limited chromium and very little nickel. So, even though stainless, hard knife steel has limited resistance to corrosion.
Austenitic stainless retains its non-magnetic crystal structure at room temperature, usually because it has high nickel content. It is therefore not hardenable by heat treating as typical hard steels are. So as knife steel it depends on other hardening methods such as alloying elements and cold working. It is highly corrosion resistant, except to stress corrosion cracking.
These two steels are practically identical in composition. They were introduced into custom knives by Bob Loveless circa 1972.
154CM is produced by Crucible Material Corporation. It is used extensively by Benchmade Knife Company.
CPM 154 is identical to 154CM in composition, produced using CPM Process, with all the benefits of the CPM technology.
The latter two are considered premium cutlery steels for both folding knives and fixed blades.
American stainless steel manufactured by Allegheny Ludlum steel Co and Crucible steel co.
302 is a Chromium-Nickel austenitic alloy used for blenders and mixers.
303 is a non-magnetic austenitic stainless steel specifically designed to exhibit improved machinability.
303 SE is a non-hardenable austenitic chromium-nickel steel to which selenium has been added to improve machinability and non-galling characteristics.
304L is a non-hardenable, low carbon austenitic chromium-nickel steel designed for special applications.
316L is a non-hardenable, low carbon austenitic chromium-nickel steel with superior corrosion and heat resisting qualities.
321 is a non-hardenable austenitic chromium-nickel steel with a high chromium content of 18.00%.
The 400 series remains one of the most popular choices for knife makers because it is easy to sharpen and it is resistant to corrosion.
410 is a hardenable, straight-chromium stainless steel which combines superior wear resistance with excellent corrosion resistance.
416 is very similar to 410 with the addition of sulfur to improve machinability.
420 has more carbon than 410, but less than 440. As such it is softer than 440, but has a higher toughness.
420HC is a higher carbon content 420 stainless. The HC stands for "high carbon" and it can be brought to a higher hardness than 420 and should not be mistaken for it. Buck Knives uses 420HC extensively.
420J2 is an inexpensive,highly corrosion resistant steel. Knife manufacturers use this material in budget knives, also in diving knives due to its high resistance to corrosion.
440A is relatively a low cost, highly corrosion resistant stainless steel.
440B is almost identical to 440A, but has a higher carbon content range compared to 440A
440C is considered a high-end stainless steel. It is very resistant to corrosion and is one of the most common stainless alloys used for knife making. The once ubiquitous American Buck Model 110 Folding Hunter was made of 440C before 1981. 440C has highest carbon content in 440 group.
The AUS stainless steel series is produced by Aichi Steel Corporation, Japan. They differ from the AISI 4xx series because they have vanadium added to them. Vanadium improves the wear resistance, toughness, and ease of sharpening.
AUS-6 (6A) is comparable to 440A with a carbon content close to 0.65%. It is a low cost steel, slightly higher wear resistance compared to 420J.
AUS-8 (8A) is comparable to 440B with a carbon content close to 0.75%. AUS-8 is often used instead of 440C. SOG knives uses AUS-8 extensively.
AUS-10 (10A) is comparable to 440C with a carbon content close to 1.10%. It is slightly tougher than 440C.
CPM SxxV series
The SxxV series are Crucible Material Corporation stainless steels produced using CPM process.
CPM S30V, on the lower end of the SxxV steels, it has a carbon content of 1.45%. However, S30V is still considered to be a superior choice for knife making.
CPM S35VN is a martensitic stainless steel designed to offer improved toughness over CPM S30V. It is also easier to machine and polish than CPM S30V.
CPM S60V (formerly CPM T440V) (discontinued), very rich in vanadium. CPM S60V has a carbon content of 2.15%. It was an uncommon steel, but both Spyderco and Kershaw Knives offered knives of this steel, Boker still offers folders made from CPM S60V.
CPM S90V (formerly CPM T420V), has less chromium than S60V, but has almost twice as much vanadium. S90V's carbon content is also higher, resting around 2.30%
CPM S110V is the latest addition to the SxxV line. It has higher corrosion resistance than S90V and marginally better wear resistance. The additional corrosion resistance while retaining all the benefits of S90V makes this steel extremely desired for kitchen cutlery.
Japanese stainless steels, manufactured by Takefu Special Steel.
VG-1 Takefu stainless steel. Popular steel in Japanese kitchen knives.
VG-2 Middle-carbon Mo stainless blade steel.
VG-5 Synergic effect of Mo and V makes carbide finer.
VG-7/VG-8 W addition strengthens substrate and improves tempering performance.
VG-10(B/W) Takefu stainless steel, similar composition to VG-1 but also contains cobalt and vanadium. Good wear resistance and rust resistance.
San-mai A composite steel used by Knife manufacture Cold Steel in their high end knives. The core is VG-1 and the outside layers are 420j for good rust resistance.
Due to small Vanadium content VG-10 has finer grain content compared to VG-1. Cobalt and Nickel improve toughness. Overall, it has better edge stability compared to VG-1. VG-10 is widely used in Japanese kitchen knives, several western makers use it in various folders and fixed blade knives, including Spyderco, Cold Steel and Fallkniven.
American stainless steels produced by Carpenter technology using vacuum-melt™ technology.
CTS-BD1 high-carbon chromium steel that provides stainless properties with high hardness and excellent wear resistance.
CTS-20(CP) offers superior edge retention and surface finish, an ability to be machined to a fine edge, and consistent heat-treatability from lot to lot.
CTS-40C(CP) a powder metallurgy, high-carbon chromium stainless steel designed to provide stainless properties with maximum hardness.
CTS-TMT A hardenable martensitic stainless steel that combines improved corrosion resistance over Type 410 stainless with hardness up to 53 HRC and improved formability over 17Cr-4Ni.
CTS-XHP is a powder metallurgy, air-hardening, high carbon, high chromium, corrosion-resistant alloy. It can be considered either a high hardness 440C stainless steel or a corrosion-resistant D2 tool steel.
Chinese and American stainless steels; the manufacturers are unknown with the exception of 14-4CrMo which is manufactured by Latrobe Specialty Metals. (sorted by first number.)
3CR13MoV A Chinese steel; made by adding molybdenum and vanadium to the 420J2-3Cr13 formula.
5Cr13MoV It is similar to 5Cr15MoV, the hardness could be HRC 56-58. It is widely used to make high-end scissors, folding knives and hunting knives etc.
6CR12MoV It is also similar to 6Cr14MoV, 6Cr14 which are also created by Ahonest Changjiang Stainless steel Co.,Ltd.
They are produced as per customers' requests. For 6Cr14MoV grade, the hardness could be HRC 60. It is good at making razors, surgical instruments.
7CR13MoV The big difference between 7Cr13MoV and 7Cr17MoV is the content of chromium. 7Cr13MoV has less tensile strength, hardness and resistance to wear when compared with 7Cr17MoV.
7CR17MoV A Chinese stainless steel compared to 440A.
8CR13MoV A Chinese stainless steel tempered at the Rc56 to Rc58 range and used in Spyderco's, Kershaw's, and other quality knife maker's budget lines of knives. For example, Kershaw's Crown II is one of the few "name brand steel" folders that can be had for under $20 (in 2013). 8CR13MoV is often talked about in terms of a high-end budget steel. Early Byrd (the Spyderco budget line) 8CR13MoV knives were marked 440C, but tests found that the steel was something entirely different from American 440C. According to Sal Glesser, owner of Spyderco, this steel was closer to AUS-8 (AUS8) than American 440C. 8CR13MoV is often compared to AUS-8 and 440B, but it has slightly more Carbon.
8CR14MoV A Chinese steel with similar performance characteristics to AUS-8. An excellent value priced steel for its performance.
9Cr18Mo A higher end Chinese stainless steel used mostly in high-end barbering scissors and surgical tools.
14-4CrMo Manufactured by Latrobe Specialty Metals. A wear resistant, martensitic stainless tool steel that exhibits better corrosion resistance than type 440C stainless steel.
6C27 A common knife steel grade with good corrosion resistance and low hardness, mainly used in applications where the need for wear resistance is low.
7C27Mo2 Generally the same properties as Sandvik 6C27, but with improved corrosion resistance.
12C27 A grade with high hardness and good wear resistance. Takes very keen edge with ok edge holding.
12C27M Another Swedish stainless razor steel. A very pure, fine grained alloy. A grade with good wear resistance and good corrosion resistance, well suited for the manufacture of kitchen tools.
13C26 Also known as a Swedish stainless razor steel. Generally the same properties as Sandvik 12C27, but with slightly higher hardness but less corrosion resistant. The Swedish steel maker Uddeholm AB also makes a virtually identical razor steel composition known as AEB-L, which they patented in 1928. Swedish razor steel is a very pure, fine grained alloy which positively affects edge holding, edge stability and toughness.
14C28N was designed by Sandvik at Kershaw's behest to have the edge properties of 13C26 but with increased corrosion resistance by adding nitrogen and chromium. Available in Kershaw knives (as of 2012). Also in other brands as Muela knives.
19C27 A grade with very high hardness and wear resistance.
Daido stainless tool steels used for kitchen knives and scissors.
DSR1K6(M), A steel that we have no information about except the fact that it exists.
DSR7F, used for high hardness cutting parts.
DSR1K7, A steel that we have no information about except the fact that it exists.
DSR1K8, A steel that we have no information about except the fact that it exists.
DSR1K9, A steel that we have no information about except the fact that it exists.
DSR10UA, used for small scissors.
DSR1K11, A steel that we have no information about except the fact that it exists.
ATS-55, produced by Hitachi Metals. It has lower molybdenum content than ATS-34. Less wear resistant that ATS-34 and has been reported to be also less rust-resistant than ATS-34.
Kin-2, Middle-carbon Mo,V stainless blade steel.
BNG10, A steel that we have no information about except the fact that it exists.
Co-Special, A steel that we have no information about except the fact that it exists.
M390 - BOHLER M390 MICROCLEAN. Third generation powder metal technology. Developed for knife blades requiring good corrosion resistance and very high hardness for excellent wear resistance. Chromium, molybdenum, vanadium, and tungsten are added for excellent sharpness and edge retention. Can be polished to an extremely high finish. Hardens and tempers to 60-62 HRC. Due to its alloying concept this steel offers extremely high wear resistance and high corrosion resistance. Source: http://www.bucorp.com/knives.htm, http://www.bohler-edelstahl.com/files/M390DE.pdf
CPM-20CV CPM-20CV is a very high quality martensitic stainless steel, with outstanding corrosion resistance and excellent edge holding. CPM-20CV does lack the impact toughness of CPM-3V but being made with the CPM process, this steel is still very resistant to lateral stress (flex) breakage. Consider CPM-20CV for a very low maintenance, all weather cutting tool.
Several steel alloys have carbon amount close or above 3%. As usual those steels can be hardened to extremely high levels, 65-67HRC. Toughness levels are not high compared to CPM S90V steel, however, they have high wear resistance and edge strength, making them good choice for the knives designed for light cutting and slicing works.
Cowry-X produced by Daido steel using PM process. Contains 3% carbon,20% chromium, 1.7% Molybdenum and Less than 1.00% vanadium. Other elements are not published or may not even exist. Used by Hattori knives in their kitchen knives KD series.
ZDP-189 produced by Hitachi steel using PM process. Contains 3% carbon and 20% chromium. Also contains Tungsten and Molybdenum. Used by several custom knife makers and factory makers including Spyderco and Kershaw in the limited run of the Ken Onion Shallot folders. The Henckels Miyabi line markets this steel with the name "MC66".
CPM S125V produced by Crucible Material Corporation using CPM process. Contains 3.25% carbon, 14% chromium and 12% Vanadium and other alloying elements. Exceptionally high wear resistance, making it difficult to process and machine for knifemakers. At first only used in custom knives, it has been utilized by larger manufacturers more recently in limited quantities.
CPM REX series
CPM REX 121, is a new high vanadium cobalt bearing tool steel designed to offer a combination of the highest wear resistance, attainable hardness, and red hardness available in a high speed steel.
CPM REX 20 (HS) is a cobalt-free super high speed steel made by the CPM process.
CPM REX 45 (HS) is an 8% cobalt modification of M3 high speed steel made by the CPM process.
CPM REX 54 HS is a cobalt-bearing high speed steel designed to offer an improvement in the red hardness of the popular M4 grade, while maintaining wear properties equivalent to M4.
CPM REX 66 (HS) is a super high speed steel made by the CPM process.
The steels in this category have much higher resistance to elements and corrosion than conventional stainless steels. They are used in knives designed for use in aggressive, highly corrosive environments, such as saltwater, areas with high humidity like tropical forests, swamps, etc.[dubious– discuss]
H1, produced by Myodo Metals, Japan. Used by Spyderco in their salt water/diving knives. Benchmade used it as well, later replaced with X15TN.
X15Tn, French steel, originally designed for medical industry and jet ball bearings. Used by Benchmade in their salt water/diving knives.
N680, Bohler-Uddeholm steel, highly corrosion resistant. Used by Benchmade in their salt water/diving knives.
N690CO an Austrian stainless steel hardened to the high Rc50 range. Currently found in Spyderco's Hossom knives and the recently discontinued Italian-made Volpe. TOPS knives also used it in their C.Q.T magnum 711 knife. Also used extensively by Fox Knives Military Division and Extrema Ratio.
Carbon steel is a popular choice for rough use knives. Carbon steel tends to be much tougher and much more durable, and easier to sharpen than stainless steel. They lack the chromium content of stainless steel, making them susceptible to corrosion.
Carbon steels have less carbon than typical stainless steels do, but it is the main alloy element. They are more homogeneous than stainless and other high alloy steels, having carbide only in very small inclusions in the iron. The bulk material is harder than stainless, allowing them to hold a sharper and more acute edge without bending over in contact with hard materials. But they dull by abrasion quicker because they lack hard inclusions to take the friction. This also makes them quicker to sharpen. Carbon steel is well known to take a sharper edge than stainless.
The 10xx series is the most popular choice for carbon steel used in knives. They are very durable.
1095, a popular high-carbon steel for knives; it is harder but more brittle than lower carbon steels such as 1055, 1060, 1070, and 1080. It has a carbon content of 0.90-1.03% Chances are, your great-grandfather's pocket knife and kitchen knives were made of 1095. It is still popular with many bushcrafters and survivalists due to its toughness and ease of sharpening. With a good heat treat, the high carbon 1095 and O-1 tool steels are often considered better than all but the most exotic and expensive stainless steels.
1084, carbon content 0.80-0.93%
1070, carbon content 0.65-0.75% Used in machetes.
1060, used in swords. It has a carbon content of 0.55-0.65%
1055, used in swords and machetes often heat-treated to a spring temper to reduce breakage. It has a carbon content of 0.48-0.55%
V-1/V-2 Chrome is added to improve quenching performance.
V-2C, Pure carbon steel, with impure substances completely removed.
a Japanese exotic, high-end steel made by Hitachi. The "Blue" refers to, not the color of the steel itself, but the color of the paper in which the raw steel comes wrapped.
Aogami/Blue-Num-1 A steel with higher tensile strength and sharpening ability than blue-2.
Aogami/Blue-Num-2 A steel with higher toughness and wear resistance than blue-1.
Aogami/Blue-Super A steel with higher Toughness, tensile strength and edge stability than all other steels in its series.
Aogami/Super blue The same steel as Blue-Super A
Is the 'purest' carbon steel and sees use in high end yanagiba from various manufacturers.
Shirogami/White-1 Hardest of the Hitachi steels, except for A/B-S and will get scary sharp, but lacks toughness.
Shirogami/White-2 Tougher than S/W-1 but not as much carbon, thus slightly less hard.
Other proprietary steels
INFI, a unique steel used in Busse knives. It is a tough steel, that resists both wear and stains. It has a carbon content of 0.50%
Other carbon steel
These steels did not exist in a series.
Shiro-2 Cr and Ni are added for better quenching and ductility.
The group of these steels is unknown at this time. Please move them to their proper group and provide a description.
Vanax By Uddeholm. A new blade steel in which carbon is largely replaced by nitrogen.
Ceramics are harder than metals but more brittle. Ceramic knives can be sharpened with silicon carbide or diamond sandpaper but chip when sharpened on a hard stone or lap. Good for those who do not sharpen their own knives.
The harder ceramics may be used in composite form to make them workable.
Very hard and strong, but expensive. Used by Böker.
Artificial glass is used to slice thin samples of soft biological materials for transmission electron microscopes. Glass breaks to form an edge that is sharper than can be ground or lapped onto a metal blade.
These materials did not fit into the aforementioned steel or ceramic types.
Titanium is often used in diving and bomb squad knives due to its rust-resistance and non-magnetic properties. On its own, titanium is a softer metal, leading to an edge that is lacking. Many custom makers graft on a carbide edge to deal with this problem. Titanium Alloy Grade 5, also known as Ti6Al4V, Ti-6Al-4V or Ti 6-4, is at least three times stronger than stainless steel.
Damascus steel - refers to either pattern welded steel or the ancient crucible steel (wootz, pulad, bulat)
Metal glasses may be used in the future, as they have properties intermediate between metals and ceramics.
Plastic, disposable or non-disposable (e.g., polycarbonate) - strong and sharp enough, if serrated, to cut many foods when eating, or for some food preparation. Less likely to scratch non-stick cookware.