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:

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

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%.

These two steels are practically identical in composition. They were introduced into custom knives by Bob Loveless c. 1972.^{[citation needed]}