Understand Knife Blade Steel Types

There are literally thousands of types of steel. Among them, the most common are carbon steels, alloy steels, tool steels, and stainless steels. Each of these types of steel has a designation system that gives them a specific number. Plain carbon steels are steels that contain iron, carbon, and a small amount of manganese. In contrast, alloy steels have a specified composition and contain certain percentages of vanadium or molybdenum, and they also typically have a larger amount of manganese. Tool steel contains tungsten, molybdenum, and other alloying elements. Four main characteristics differentiate steels from one another — corrosion resistance, hardness, toughness, and wear resistance.
Hardness is a measure of a steel’s resistance to deformation. Hardness in knife steels is most commonly measured using the Rockwell C test. Hardened knife steels are generally about 58/62 HRC (hardness Rockwell C), depending on the grade. Most are typically about 58/60 HRC, although some are occasionally used up to about 62 HRC. Knife edges which plastically deform in service possess insufficient hardness. Permanent bending of the blade or permanent deflection of the cutting edge indicates insufficient hardness. Because a steel’s resistance to permanent deflection is directly related to the hardness, not the grade, corrective actions for deformation may include increasing hardness, or decreasing operating loads by increasing blade thickness. Changing grades will not help a deformation problem, unless the new grade is capable of higher hardness.
Toughness, as considered for high hardness knife steels, is the relative resistance of a material to breakage, chipping, or cracking under impact or stress. Toughness may be thought of as the opposite of brittleness. Toughness testing is not as standardized as hardness testing. It may be difficult to correlate the results of different test methods. Common toughness tests include various impact tests and bend fracture tests. In service, wear failures are usually preferable to toughness failures (breakage). Breakage failures can be unpredictable, catastrophic, and even a safety concern. Conversely, wear failures are usually gradual, and can be anticipated and planned for. Toughness failures may be the result of inadequate material toughness, or a number of other factors, including heat treatment, fabrication (grinding abuse), or a multitude of usage issues. Toughness data is useful to predict which steels may be more or less prone to chipping or breakage than other steels, but toughness data cannot alone predict the performance life of a knife.
Wear Resistance
Wear resistance is the ability of material to resist being abraded or eroded by contact with work material, or outside influences (dirt, grit, bone, etc.) Wear resistance is provided by both the hardness level and the chemistry of the knife blade. Wear tests are quite specific to the circumstances creating the wear and the application of the knife. Most wear tests involve creating a moving contact between the surface of a sample and some destructive medium. There are 2 basic types of wear damage in knives, abrasive and adhesive. Wear involving erosion or rounding of edges is called abrasive wear. Abrasive wear does not require high pressures. Abrasive wear testing may involve sand, sandpaper, or various slurries or powders. Wear from intimate contact between two relatively smooth surfaces, such as steel on steel, carbide on steel, etc., is called adhesive wear. Adhesive wear may involve actual tearing of the material at points of high pressure contact due to friction.
Corrosion Resistance
Corrosion Resistance is a measure of a knife steel’s resistance to attack in high humidity, damp, or salt environments. This resistance is established by the addition of chromium to the composition. Developing corrosion resistance in a heat treatable, wear resistant steel is a challenge that has been met with numerous specialty CPM alloys. Relative resistance is often measured in salt spray and water spray environments.
Steel Types Overview
13C26 Sndvik Steel: A scandinavian steel similar to 440A Stainless but considered more corrosion resistant. (.68 Carbon, .13 Chromium) 3CR13: A Chinese Stainless steel that is similar in quality to 420J2 (AUS 4) stainless steel. The following formula is a break down in the steel: Around 13% chromium and 3% carbon. It has a HRC of 52-55 making it relatively soft. 5CR13: A Chinese Stainless steel that is similar in quality to 420HC (AUS 6) stainless steel. The following formula is a break down in the steel: Around 13% chromium and 5% carbon. It has a HRC of 54-57 making it relatively soft. 7CR17MoV: A Chinese Stainless steel that is similar in quality to AUS6 stainless steel. The follwoing formula is a break down in the steel: 7CR part means it is 7% chromium and the 17MoV means .17% molybdenum and .17% Vanadium 8cr13MoV: A Chinese Stainless steel that is similar in quality to AUS8 stainless steel. The follwoing formula is a break down in the steel: 8CR part means it is 8% chromium and the 17MoV means .17% molybdenum and .17% Vanadium 10 Series Carbon Steel: Also known as 10XX. 10 is an SAE designation for plain carbon steel. (1 means carbon, 0 denotes no other major element in the steel) The numbers following the ten give the amount of carbon added to the steel alloy. For instance 1070 would equal 0.70% or 7/10 of 1% of carbon added to the steel. 1050 equals ½ of 1% or 0.50%. More carbon produces a harder, tougher blade but increase the potential for staining (rust). See also 1095. 12C27: A Steel with .6% carbon that originated in Scandinavia. It is roughly equivalent to 440A. It is often called Norwegian Steel 154CM: Known as a crucible stainless steel, it is one of the newer stainless steels which, depending on manufacturer is as good or better than 440c or ATS 34 stainless steel. The Rockwell test is around HRC 58-61. A popular use for 154CM is in survival knives that may be exposed to salt water for long periods of time. 154CM stainless steel contains: Carbon 1.05%, Chromium 14.00%, Manganese 0.50%, Molybdenum 4.00%, and Silicon 0.30% 304 Stainless Steel: Grade 304 is the standard “18/8” stainless; it is the most versatile and most widely used stainless steel. The steel contains 18% chromium and 8 % nickel. The steel is austenitic (non-magnetic) due to the high chromium content but is used in surgical instruments due to it high stainless content. They use it mainly for pans and throw away blades. It would make an absolutely lousy knife blade due to the softness of the metal yet in theory it is a Surgical Steel. The steel is often used for dining sets. 316 Stainless Steel: Grade 316 is the standard molybdenum-bearing grade stainless steel, second in importance to 304 amongst the austenitic (non-magnetic) stainless steels. It is a surgical stainless steel. The molybdenum gives 316 better overall corrosion resistant properties than Grade 304, particularly higher resistance to pitting and crevice corrosion in chloride environments. The steel is non magnetic and makes a lousy knife blade. However, 316 is often used for other knife materials where edge retention is not required but corrosion resistance is highly valued. For this reason, it is a U.S. Military standard for marlin spikes on folding rigger knives used by the Navy and Coast Guard. 400 Series Stainless: A term almost as misleading as “Surgical Steel” This can be any 400 series stainless from 403 or 440F. The smart consumer will assume it is alesser grade steel, typically 420 or 420J@ 420 Stainless Steel: A low carbon content (less than .5%) stainless steel which is extremely stain resistant but soft, making it a poor choice for every day or rough use. It is, however a good choice for knives used around salt water (diving) and for decorative knives because of its rust resistant qualities. It is often used in cheap imports. This is probably the steel they are referring to when a company advertises “Surgical Steel.” It dulls quickly and is easily nicked, bent, blunted or broken due to being a soft steel. It is some times used as the liners on pocket knives instead of the more popular brass. 420F: A stainless Steel with 12-14 Chromium and .15% carbon, used mostly in dental instruments. 420HC: A 420 stainless modified with more carbon, and normally a better heat treatment. It is said to be roughly comparable to 440A. There is debate about this claim. Buck uses this in its Chinese imports as well as many of its USA made knives. It is also used by others. 420J Stainless Steel: Is a low carbon stainless steel which is used in lot of inexpensive imports, Some knife makers use it in the liners of their folding knives but not for blades. 420J is often called quality surgical steel or Japanese steel. (The J has nothing to do with Japanese made steel). 420J has a high chromium content that gives it great corrosion resistance but is has lousy edge retention. It is a very soft steel whcih means it will knick and dull quickly. It is often used in Novelty and Art/Decorative knives 420J2 Stainless Steel: 420J Stainless with a little more carbon. It is sometimes used in dive knives because for its corrosion resistance. It is used in surgical instruments due to ease of machining and corrosion resistance. With proper heat treating can achieve a Rockwell test of 56; which makes it comparable to 420HC. It is often used in scissors. It is not a true tool steel. However, because it is used on making certain surgical tools some people will call it 420J2 tool steel in a less than scrupulous sales pitch. 425M: A stainless steel used by Buck Knives with about .5% carbon, It is about the same as 440a Stainless Steel. 440 Razor Sharp Steel: A Rough Rider Trademark blade etch normally found on the reverse side of the main blade. While not specified, these knives usually have a Rockwell hardness rating of around 56-58HRC. 440 Stainless Steel: Any of the 440 series Stainless Steel. When not specified it should be considered 440 A. 440 Series Stainless Steel: A term used to specify any of the 440 Stainless Steels. (440A, 440B, 440C) Companies use the vague term for a number of reasons but it is probably used so that different types of 440 steel with varying heat treatments can be used on different blades without having to be specific. This can be good or bad. Assume that the steel will be 440A unless it is verified otherwise. 440 Tested Sharp (Anvil): Another Rough Rider Trademark blade etch used on their 440 series stainless steel. It is normally found on the obverse side of the main blade. While not specified, these knives usually have a Rockwell hardness rating of around 56-58HRC. 440A Stainless Steel: A common stainless steel considered good acceptable for every day use. It has good rust resistance, and holds a reasonable edge and sharpens easily. Carbon content is around .65-.75% Chromium is 16-18% and is around Molidium .75%. When a knife is marketed as 440 Stainless, this is the steel they mean. 440A has a maximum hardness of 56HRC. 440B Stainless Steel: Stainless Steel with a minimum of 0 .9% carbon. 440Bis tougher and will handle more abuse than 440A but will rust more easily. 440B has a maximum hardness of 58HRC. You normally do not see blades made with 440B steel. Most often they are made with the Japanese equivelent steel AUS8 steel. 440C Stainless Steel: Stainless Steel with a minimum of 1.2% carbon This is the hardest of the 440 series It takes more abuse however it also rusts more easily than the other 440 series stainless steels. 440C can achieve a 60 HRC. At one time it was considered a stainless “Super Steel” 4116 Krupp Stainless Steel: 4116 is a fine grained, stainless steel made by ThyssenKrupp in Germany It was developed for the medical industry but is now used in food preperation. The balance of carbon and chromium content give it a high degree of corrosion resistance and also impressive physical characteristics of strength and edge holding. Edge retention is said to be on par with 440C Stainless Steel but corrosion resistance is much better. Carbon: 0.45-0.55; Si: 1.00 Mn: 1.00; P:0.040; Cr: 14.0-15.0, Mo: 0.50-0.80, V: 0.10-0.20 5160: A carbon-chromium steel alloy, often refered to as Spring Steel because it is used in car springs. It is a common sword steel, especially for European style swords but is also common among survival knives due its tougness. The compostion of 5160 is: Carbon -0.56 – 0.64; Chromium -0.7 – 0.9; Manganese -0.75 – 1; Phosphorus – 0.035 max; Silicon – 0.15 – 0.35; and Sulphur – 0.04 max. 6150: A CV steel with a medium to high carbon content (.50%) used in making automobile springs 6195: A CV steel steel with a high carbon content (.95% )used in making ball bearing. 1060: A steel commonly used for Swords. It is often compared to 5160 steel with 5160 normally being considered the better of the two As this is a series 10XX steel, its carbon conten is around .60% giving it great toughness but poor edge retention something normally not considered important when doing major hacking.. 1070, 1075: 1070 and 1075 are common carbon steels used in machetes and large cutting blades such as Kukris. the 70 and 75 refers to the amount of carbon (.70 or .75%) used in the blade construction. The steel will dull faster than 1095. On the other hand, it is tougher and thus can absorb more hacking punishment than 1095. 1080, A carbon steel blade used on survival combat knives and some of the better quality Kukris. 1095: 1095 is the steel used in many US Military fighting knives and is the de-facto industry standard for combat knives. It is one of the 10-series steels. The 95 stands for .95% carbon content in the steel. A2 Tool Steel (carbon steel): A2 is the most common air hardening grade of tool steel currently used. It contains 1.0% carbon, 5.0% chromium, and 1.0% molybdenum. It is not a stainless steel. Assisted Opening: A knife that uses a spring or other device to assist in the opening of the blade. Unlike switchblades, assisted opening knives require the operator to touch the blade in order for it to open. This is usually done with the aid of thumb stud that is an integral part of the blade. ATS-34: A stainless steel considered superior to 440C Stainless Steel in most aspects but may not be as tough. AUS-6: Japanese stainless steel, roughly comparable to, if not slightly better than 440A (AUS-6, .65% carbon) AUS-8: Japanese stainless steel, roughly comparable to, if not slightly better than 440B (AUS-6, .75% carbon) AUS-10: Japanese stainless steel, roughly comparable to, if not slightly better than 440C (AUS-1.1% carbon) Austentic Stainless Steel. Stainless steel with at least 7% nickel added, making the steel virtually useless for a knife blade. Austentic stainless steel is normally non magnetic and is sometimes used for knife handles or liners due to its softeness. BG-42. A stainless steel with 1.15% Carbon, .50 Magnesium, .30 Silicon, 14.5 Chromium, 4.0 Molydium, and 1.5 Vanadium. It is consdiered a a forerunner to S30V. It is considered hard to work but has exellent edge retention but somewhat brittle.. HRC 61-63. It is better than 440C but not as good as S30V C45 Steel: A carbon steel .45 Carbon, .4 Si, .65 Mn, .10 Mo, .40 Ni used in hand tools such as Hammers and Axes. Also known as 1045 tool steel. Carbon Steel: Steel with at least 0.4% carbon. Other trace elements do not need to be specified. Also known as W Steel or Plain Carbon Steel CV Steel:1095 Steel with added Chromium (1%) and Vanadium (.18%) to improve hardening and strength. The term usually refers to knives made by W.R. Case & Son but others also use the steel. It is sometimes referred to as a semi-stainless carbon steel due to the added chromium. D2 Tool Steel (semi-stainless / carbon steel): D2 is a wear resistant steel used for various cutting tools such a shears and planers. It was first developed around the time of World War II It contains 1.5% carbon and 11.0 – 12.0% chromium; additionally it is composed of 0.45% manganese, 0.030% max phosphorus, 0.030% max sulfur, 1.0% vanadium, 0.7% molybdenum, and 0.30% silicon. It is a popular knife steel due to its edge retention. Its major draw back is that when it becomes dull, it is harder to sharpen. Dues to its high chromium content it is often considered a semi-stainless steel. Damascus Steel: Two or more types of steel of differing grades are heated and forge welded to create patterns in the blade. The blades are then acid etched to further bring out the varying patterns of light and dark steels. There is a myth that this somehow make the steel stronger and more resilient. In fact the steel is going to possess the weakest qualities of both steels. Damasscus Steel is more correctly termed Pattern Welded Steel and alsmost always is made with carbon steel and is prone to rusting. Many high-end custom knife makers use damascus steel because of the ability to fold a varity “patterns” in the steel. Ferritic Stainless Steel: Ferritic stainless steels have approximately of 17% chromium. Ferritic steel is less ductile than austenitic steel and is not hardenable by heat treatment. It makes lousy knife blade but is a type of surgical stainless steel. File Steel: A tool steel used in the manufacturing of files. It is also known as the ASTM standard W1 Steel. When .2% vanadium is added it to W1 Steel it is known as W2 steel. This is a type of steel is sometimes used when making Damascus steel. H-1 Super Steel: A precipitation-hardened steel containing nitrogen and designed to be rust proof. The steels composition is: Carbon-0.15%, Chromium-14.00-16.00%, Manganese-2.00%, Molybdenum-0.50-1.50%, Nickel-6.00-8.00%, Nitrogen-0.10%, Phosphorus-0.04%, Silicon-3.00-4.50%, Sulfur-0.03%. Spyderco uses the steel for dive and rescue knives that are expected to be used in high corrosion environments such as salt water. The HRC is said to be in the high 50s but Spyderco does not perform Rockwell testing on the steel. Most consider it to be on par with AUS6 or AUS 8 steel in edge retention and durability. High Carbon: A term meaning a blade has more carbon than is normally found in the particular grade of steel. Unless you know the grade of the steel, the term is meaningless. High Carbon Tool Steel: Steel in which the carbon content exceeds 0.6%. but is less than 1%. Inox: The French term for Stainless Steel and as such a common term for stainless steel in many European countries where French is spoken. As the term Inox was was adopted by the Victoria Knife Company (now Victorinox) for its stainless steel blades, many consider it to mean a certain type of stainless steel. This really is not the case. In fact the term is just as generic as Rostfrei and Surgical Steel. (See also Rostfrei and Surgical Steel) J2 Tool steel: A non-sensical term often applied to 420J2 Stainless Steel to make a person think they are buying a better quality knife. There is no such thing as J2 Tool Steel, the seller is refering to 420J2 stainless steel. While it is used to make some tools, it is not truly a “Tool Steel” Japanese Steel: A non-descriptive term for stainless steel manufactured in Japan. Unless specified it could mean anything. The dealer is hoping you think it is at least AUS 6 Stainless steel. A steel manufactured in Japan that is equivalent to 440 A Stainless steel. Unless specified it is meaningless. There are many types of Japanese steels. L6 Tool Steel (carbon steel): L6 is an oil-hardening tool steel that is characterized by very good toughness. It contains approximately 1.25-2.0% Nickel, 0.65-0.75 % Carbon, 0.6 – 1.2% Chromium and 0.25 – 0.8% Manganese. It has a maximum of 0.5% Molybdenum. Martensitic Stainless Steel: Martensitic steels are low carbon steels built around the Type 410 compostion It normally contains 12% chromium, and 0.12% carbon. While Martensite gives great hardeness to the steel it also casue the steel to be brittle so few steels are fully hardened. Norwegian Steel: The term normally refers to a stainless steel with .6% carbon. It originated in Scandinavia. It is roughly equivalent to 440A. Also known as 12C27 Stainless Steel. O-1 Tool Steel (carbon steel): O-1 is a carbon steel used by the Randall Knife Company. It is proven superior to 1095 Carbon Steel. It contains 0.90% carbon 1.0%–1.4% manganese, 0.50% chromium, 0.50% nickel, and 0.50% tungsten.. It can be hardened to about 57-61 HRC. Pattern Welding: See Damascus Steel Plain Carbon Steel: See Carbon Steel Pot Metal: See Zamak S30V: A registered trademarked steel of Crucible Industries LLC. It is more correctly called CPM S30V. It is a stainless steel with a compostion of Carbon 1.45%, Chromium 14.00%, Vanadium 4.00%, Molybdenum 2.00%. The Steel was developed by Dick Barber of Crucible Materials Corporation in collaboration with knifemaker Chris Reeve. CPM S30V is considered one of the Super Steel and is normally found in high-end tactical knives. Sandvik Steel: Stainless steel of Scandinavian origin. Sandivk 13C26 is similar to 440A Stainless SK-5: A Japanese high-carbon and also includes manganese. It is said to be a tough steel with good edge retention Carbon: 0.80%; Si: 0.15-0.35% ; Mn 0.15-0.50% Spring Steel : 5160 Steel is often called spring steel because it was often used in the making of leaf springs for automobiles. It is aslo called Studebaker Steel because many knife makers used the steel specifically from the leaf springs of old Studebakers for knife blades. It is a carbon-chromium steel alloy, . It is a common sword steel, especially for European style swords but is also common among survival knives due its tougness. The compostion of 5160 is: Carbon -0.56 – 0.64; Chromium -0.7 – 0.9; Manganese -0.75 – 1; Phosphorus – 0.035 max; Silicon – 0.15 – 0.35; and Sulphur – 0.04 max. Stainless Steel: A steel chromium alloy with approximately 10% to 18% chromium added to the steel. Stainless steel will still rust or stain. It is just less prone to rusting and staining. A lower chromium level is normally ideal for blade steel but will be more prone to rusting. Surgical Steel: Almost any type of stainless steel can be classified as “surgical steel” making the term surgical steel virtually meaningless. Surgical steels includes the 300 series or 18-8 Stainless which have a make up 18% chromium and 8% nickel. These steels are used in surgery for prosthetics, as well as surgical trays. They are also used for making dinner wear because they are very stain/rust resistant. 18-8 Stainless is virtually useless as a knife blade because edge retention is virtually non-existent. You can’t sharpen it! A quick test is a magnet test. 18-8 steel is so full of nickel, chromium or other alloys that it isn’t even magnetic! However, there are some surgical steel that is magnetic and the quality is worse than the worst 420 Stainless, at least for knife blades. The novice knife collector should assume that any knife passed off as surgical steel is no better than 420 even if it passes the magnet test. A better quality steel would be listed by an actual grade. The exception to this rule is if you already familiar with other knives of the same brand and know them to be of good quality. Tool Steel: Varying grades of carbon steel used in the making of tools. Tool steel tends to be harder and have greater edge retention. Tool steel is more prone to rusting than stainless steel. It is used by high-end custom knife makers, and in some Damascus blades. Unfortunately unless the person says what type of tool steel is being used, it becomes a somewhat innocuous term that is meaningless. Assume that if the type of tool steel is not mentioned, it is just plain-carbon steel, the lowest grade of tool steel. Tru-Sharp Surgical Steel: Steel used in the manufacturing of many Case knives. It is believed to be 425M or 420HC stainless. They tend to have an HRC of around 56-58. VG-10: A cutlery quality steel made by Takefu Special Steel co of Japan. Its prpoerties are Carbon:1.0% Chromium:15.0% Molybdenum:1.0% Vanadium:0.2% Cobalt:1.5% The steel is used by Spyderco and Kershaw. Itwas orginally designed for kitchen cutlery but quickly was adopted for sport and survival cutlery. It is often referred to a “Super Steel” due to its quality. W Grade Tool Steel: Carbon steel that is quenched with water. It is also called carbon steel or plain carbon steel. Carbon content should be at a minimum of 0.4% to qualify as plain carbon steel. Other elements such as molybdenum and nickel are not specified. It is considered a “high” carbon tool steel if the carbon content exceeds 0.6%. Zamak (Zamack) : A trademark name for any variety of Zinc alloys sometimes used in the production of knife scales. Zamak is zinc alloy with around 3-5% aluminum added as well as a small percentage of Copper and magnesium. It is disparagingly called “pot metal”. Despite the claims I have never seen it used for blade steel. When it comes to knives, zamak is often used for knife handles, cross-bars hilts, etc. instead of more expensive metals such as brass, aluminum or 420 stainless steel. It has the dull luster of pewter but is sometimes electroplated with brass to give it a brass finish. It is a soft, brittle metal which does not stand up to harsh use.

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