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A variety of blade materials can be used to make the blade of a knife or other simple edged hand tool or weapon, such as a sickle, hatchet, or sword. The most common blade materials are carbon steel, stainless steel, tool steel, and alloy steel. Less common materials in blades include cobalt and titanium alloys, ceramic, obsidian, and plastic.
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 a material has. This differs from other scales such as the Mohs scale (scratch resistance testing), which is used in mineralogy. As hardness increases, the blade becomes more capable of taking and holding an edge but is more difficult to sharpen and increasingly more brittle (commonly called less "tough").[ citation needed ] Laminating harder steel between softer steel is an expensive process, though it gives the benefits of both "hard" and "soft" steels to some extent (see San mai and Damascus steel).
Tool steel grades used in cutlery: A, D, O, M, T, S, L, W. See also AISI Tool Steel Grades.
The following are tool steels, which are alloy steels commonly used to produce hardened cutting tools:
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Crucible Industries [13] produces Crucible Particle Metallurgy (CPM) tool steels using a powder metal forge process. [14]
Chrome steel is one of a class of non-stainless steel that is used for applications such as bearings, tools, and drills.
Steels that did not fit into the stainless category because they may not have enough of a certain element, such as chromium.
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. For a steel to be considered stainless it must have a Chromium content of at least 10.5%. [24]
These two steels are practically identical in composition. [25] They were introduced into custom knives by Bob Loveless c. 1972.[ citation needed ]
The latter two are considered premium cutlery steels for both folding knives and fixed blades. [7]
Because the 300 series is non-hardenable (non-Martensitic), they are primarily used in entry-level dive knives and as the outer layers in a San Mai blade.
400 series
420 series contains several types with various carbon content between 0.15% and 0.40% this steel grade is widely used to make high-end razor blades, surgical scalpels, etc. It obtains about 57 HRC after suitable heat treatment.
420HC (420C) is a higher carbon content 420 stainless steel. The HC stands for "high carbon" and it can be brought to a higher hardness than regular 420 and should not be mistaken for it. Buck Knives, Gerber Knives and Leatherman use 420HC extensively. [7] 420A (420J1) and 420B (420J2) are economical, highly corrosion-resistant stainless steel grades. Knife manufacturers use this material in budget knives, also in diving knives due to its high corrosion resistance. [7]
440 series has three types: 440A, 440B, and 440C. 440A is a relatively low-cost, highly corrosion-resistant stainless steel. In China, A honest Changjiang Stainless Steel developed 7Cr17MoV, a modified 440A, by adding more Vanadium. [34] 440B is almost identical to 440A but has a higher carbon content range compared to 440A. [34] 440C is also highly corrosion-resistant but is capable of having a very high hardness. The hardenability of 440C is due to it having the highest carbon content in the 440 group. Because of this, 440C is one of the most common stainless alloys used for knife making. [34] The once ubiquitous American Buck Model 110 Folding Hunter was made of 440C before 1981.[ citation needed ] Böhler n695 is equivalent to 440C.[ citation needed ] Knife blades specified as being "440" can typically be assumed to be the lower-hardness 440A grade.[ citation needed ]
AUS series
The AUS stainless steel series is produced by Aichi Steel Corporation of 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. [7] In the alloy name the appended 'A' indicates the alloy has been annealed.
CPM SxxV series
The SxxV series are Crucible Industries [13] stainless steels produced using CPM process. [14]
Japanese stainless advanced alloy steels, manufactured by Takefu Special Steels. [42] As all Steel manufacturers have their secret undisclosed elements in their alloys, the main parts are mostly known to public, and when there was a demand for High-end Cutlery in the kitchen Takefu was one of the first with a so-called Alloy Steel that required little to no maintenance for daily home cook users as well as the professional kitchen. Even today it remains one of the most looked Steels worldwide.
Due to extreme demand 10 years ago and Chinese counterfeits, the steel has been excluded from the Japanese market only and no longer can be exported from outside Japan. Chinese counterfeiting of steels where not even close to resembling the original steel and quality and therefore the decision was purely made to retain the high quality of VG steels and make the steel exclusively available for Japanese blacksmiths and manufacturers only making it nowadays a rare and exclusive high-end steel. Although old retailers outside Japan may have had a large quantity from the early days, it is officially no longer available outside Japan and only the finished products can be exported from Japan. [ citation needed ]
Due to the small vanadium content and several undisclosed changes, VG-10 has a finer grain content compared to VG-1. Cobalt and nickel improve toughness. Overall, it has way better edge stability compared to VG-1. VG-10 is widely used in Japanese kitchen knives, several manufacturers have used it in various folders and fixed blade knives, but no longer use it, including Spyderco, Cold Steel and Fallkniven. [7]
American stainless steels are produced by Carpenter Technology using vacuum-melt technology.
Chinese and American stainless steels; the manufacturers are unknown except 14-4CrMo which is manufactured by Latrobe Specialty Metals.
(The following are sorted by first number.)
Daido stainless tool steels are used for kitchen knives and scissors.
Several steel alloys have carbon amounts close to or above 3%. As usual, those steels can be hardened to extremely high levels, 65–67 HRC. Toughness levels are not high compared to CPM S90V steel, however, they have high wear resistance and edge strength, making them a good choice for knives designed for light cutting and slicing works.
The steels in this category have much higher resistance to elements and corrosion than conventional stainless steels. These steels are austenitic and non-magnetic. They are used in knives designed for use in aggressive, highly corrosive environments, such as saltwater, and areas with high humidity like tropical forests, swamps, etc. These steels can contain 26% to 42% chromium as well as 10% to 22% nickel and 1.5 to 10% of titanium, tantalum, vanadium, niobium, aluminum silicon, copper, or molybdenum, etc., or some combination thereof.[ citation needed ]
Carbon steel is a popular choice for rough-use knives and cheaper options. Carbon steel used to be much tougher, much more durable, and easier to sharpen than stainless steel. This is no longer the case since the coming of super-advanced alloy metallurgy such as VG-10 and SG-2 powder steel for example. These high-end stainless alloys now have all the benefits including hardness, toughness, and corrosion resistance, and passed the limits of Carbon steel. Carbon steels lack the chromium content of stainless steel, making them very susceptible to corrosion. [7]
Carbon steels have less carbon than typical stainless steels, but it is the main alloy element. They are more homogeneous than stainless than other high alloy steels, having carbide only in very small inclusions in the iron. The bulk material is a little bit harder than standard stainless steel such as St-304 (high-end alloys excluded), allowing them to hold a sharper and more acute edge without bending over in contact with hard materials. But they dull by abrasion much quicker, because they lack hard inclusions to take the friction. This also makes them quicker to sharpen but less edge-resistant. The only advantage they now hold over high-end stainless steel alloys is much lower production costs. This keeps product prices fairly low.
The 10xx series is the most popular choice for carbon steel used in knives as well as katanas. They can take and keep a very sharp edge. [59]
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.
These steels did not exist in a series.
The group of these steels is unknown at this time.
There is no "best" knife steel that can accomplish all objectives. From the bewildering array of available steels, the following represent reasonable choices of steels, based on metallurgical considerations and extensive testing relevant to knife applications [60]
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.
The harder ceramics may be used in composite form to make them workable.
Very hard, strong, and corrosion-resistant, but expensive. Used by Böker.
An alloy is a mixture of chemical elements of which in most cases at least one is a metallic element, although it is also sometimes used for mixtures of elements; herein only metallic alloys are described. Most alloys are metallic and show good electrical conductivity, ductility, opacity, and luster, and may have properties that differ from those of the pure elements such as increased strength or hardness. In some cases, an alloy may reduce the overall cost of the material while preserving important properties. In other cases, the mixture imparts synergistic properties such as corrosion resistance or mechanical strength.
Stainless steel, also known as inox, corrosion-resistant steel (CRES), and rustless steel, is an alloy of iron that is resistant to rusting and corrosion. It contains iron with chromium and other elements such as molybdenum, carbon, nickel and nitrogen depending on its specific use and cost. Stainless steel's resistance to corrosion results from the 10.5%, or more, chromium content which forms a passive film that can protect the material and self-heal in the presence of oxygen.
High-strength low-alloy steel (HSLA) is a type of alloy steel that provides better mechanical properties or greater resistance to corrosion than carbon steel. HSLA steels vary from other steels in that they are not made to meet a specific chemical composition but rather specific mechanical properties. They have a carbon content between 0.05 and 0.25% to retain formability and weldability. Other alloying elements include up to 2.0% manganese and small quantities of copper, nickel, niobium, nitrogen, vanadium, chromium, molybdenum, titanium, calcium, rare-earth elements, or zirconium. Copper, titanium, vanadium, and niobium are added for strengthening purposes. These elements are intended to alter the microstructure of carbon steels, which is usually a ferrite-pearlite aggregate, to produce a very fine dispersion of alloy carbides in an almost pure ferrite matrix. This eliminates the toughness-reducing effect of a pearlitic volume fraction yet maintains and increases the material's strength by refining the grain size, which in the case of ferrite increases yield strength by 50% for every halving of the mean grain diameter. Precipitation strengthening plays a minor role, too. Their yield strengths can be anywhere between 250–590 megapascals (36,000–86,000 psi). Because of their higher strength and toughness HSLA steels usually require 25 to 30% more power to form, as compared to carbon steels.
Stellite alloys are a range of cobalt-chromium alloys designed for wear resistance. "Stellite" is also a registered trademark of Kennametal Inc. and is used in association with cobalt-chromium alloys.
A Japanese kitchen knife is a type of kitchen knife used for food preparation. These knives come in many different varieties and are often made using traditional Japanese blacksmithing techniques. They can be made from stainless steel, or hagane, which is the same kind of steel used to make Japanese swords. Most knives are referred to as hōchō or the variation -bōchō in compound words but can have other names including -kiri. There are four general categories used to distinguish the Japanese knife designs: handle ; blade grind ; steel ; and construction.
Martensitic stainless steel is a type of stainless steel alloy that has a martensite crystal structure. It can be hardened and tempered through aging and heat treatment. The other main types of stainless steel are austenitic, ferritic, duplex, and precipitation hardened.
Carbon steel is a steel with carbon content from about 0.05 up to 2.1 percent by weight. The definition of carbon steel from the American Iron and Steel Institute (AISI) states:
Tool steel is any of various carbon steels and alloy steels that are particularly well-suited to be made into tools and tooling, including cutting tools, dies, hand tools, knives, and others. Their suitability comes from their distinctive hardness, resistance to abrasion and deformation, and their ability to hold a cutting edge at elevated temperatures. As a result, tool steels are suited for use in the shaping of other materials, as for example in cutting, machining, stamping, or forging.
High-speed steel is a subset of tool steels, commonly used as cutting tool material.
In cooking, a chef's knife, also known as a cook's knife, is a cutting tool used in food preparation. The chef's knife was originally designed primarily to slice and disjoint large cuts of beef and mutton. Today it is the primary general utility knife for most Western cooks.
Case-hardening or carburization is the process of introducing carbon to the surface of a low-carbon iron, or more commonly a low-carbon steel object, in order to harden the surface.
Tempering is a process of heat treating, which is used to increase the toughness of iron-based alloys. Tempering is usually performed after hardening, to reduce some of the excess hardness, and is done by heating the metal to some temperature below the critical point for a certain period of time, then allowing it to cool in still air. The exact temperature determines the amount of hardness removed, and depends on both the specific composition of the alloy and on the desired properties in the finished product. For instance, very hard tools are often tempered at low temperatures, while springs are tempered at much higher temperatures.
Spyderco is an American cutlery company based in Golden, Colorado, producing knives and knife sharpeners. Spyderco pioneered many features that are now common in folding knives, including the pocket clip, serrations, and the opening hole. Spyderco has collaborated with 30 custom knife makers, athletes, and self-defense instructors for designs and innovated the usage of 20 different blade materials.
Knife making is the process of manufacturing a knife by any one or a combination of processes: stock removal, forging to shape, welded lamination or investment cast. Typical metals used come from the carbon steel, tool, or stainless steel families. Primitive knives have been made from bronze, copper, brass, iron, obsidian, and flint.
The SAE steel grades system is a standard alloy numbering system for steel grades maintained by SAE International.
Alloy steel is steel that is alloyed with a variety of elements in amounts between 1.0% and 50% by weight, typically to improve its mechanical properties.
CPM S30V is a martensitic (hardened) powder-made (sintered) wear and corrosion-resistant stainless steel developed by Dick Barber of Crucible Industries in collaboration with knifemaker Chris Reeve. Its chemistry promotes the formation and even distribution of vanadium carbides, which are harder and more resistant to abrasion than chromium carbides. The powdered metallurgy process reduces the size of the carbides and gives the steel a very refined grain, further improving toughness. It contains carbon 1.45%, chromium 14.00%, vanadium 4.00%, and molybdenum 2.00%. Barber received feedback from a number of other knife users and knifemakers such as Sal Glesser, Ernest Emerson, Tony Marfione, Phil Wilson, William Harsey Jr., Tom Mayo, Jerry Hossom, and Paul Bos in the development of CPM S30V.
Mangalloy, also called manganese steel or Hadfield steel, is an alloy steel containing an average of around 13% manganese. Mangalloy is known for its high impact strength and resistance to abrasion once in its work-hardened state.
VG-1 is a high Carbon (C) Molybdenum (Mo) stainless steel manufactured by Takefu Special Steel Co., Ltd. It is not the same steel as VG-10.
440C is a martensitic 400 series stainless steel, and has the highest carbon content of the 400 stainless steel series. It can be heat treated to reach hardness of 58 to 60 HRC. It can be used to make rolling contact stainless bearings, e.g. ball bearings and roller bearings. It is also used to make knife blades.
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