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"). 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).

Steel

Alloy steels

Tool steels

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:

CPM Tool Steel

Crucible Industries produces Crucible Particle Metallurgy (CPM) tool steels using a powder metal forge process.

Chrome steel

Chrome steel is one of a class of non-stainless steel that is used for applications such as bearings, tools, and drills.

Semi-stainless steels

Steels that did not fit into the stainless category because they may not have enough of a certain element, such as chromium.

Stainless steel

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%. These two steels are practically identical in composition. They were introduced into custom knives by Bob Loveless c. 1972. The latter two are considered premium cutlery steels for both folding knives and fixed blades. 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. 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. 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. 440B is almost identical to 440A but has a higher carbon content range compared to 440A. 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. The once ubiquitous American Buck Model 110 Folding Hunter was made of 440C before 1981. Böhler n695 is equivalent to 440C. Knife blades specified as being "440" can typically be assumed to be the lower-hardness 440A grade. 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. In the alloy name the appended 'A' indicates the alloy has been annealed. CPM SxxV series The SxxV series are Crucible Industries stainless steels produced using CPM process. Japanese stainless advanced alloy steels, manufactured by Takefu Special Steels. 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. 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. 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.)

DSR series

Daido stainless tool steels are used for kitchen knives and scissors.

High-chrome / high-vanadium stainless steel

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.

High-speed steel

Super stainless steels

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.

Carbon steel

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. 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. 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.

Unassigned steels

The group of these steels is unknown at this time.

Optimal Knife Steels

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

Common blade alloying elements

Ceramics

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.

Aluminum oxide ceramic (Al2O3)

Zirconium oxide (ZrO2)

Very hard, strong, and corrosion-resistant, but expensive. Used by Böker.

Other materials

Historical