O-1 TOOL STEEL, oil hardening, general purpose tool steel is perfect for knife blades due to the excellent abrasion resistance, toughness and machinability characteristics. Typical chemistry C .95, Mn 1.20, Si .30, CR .50, Va.20, Mo .50.
440-C is high-carbon chromium stainless that resists corrosion from fresh water, steam, crude oil, gasoline, stains from food acids and fruit. The excellent wear and resistant qualities of 440-C steel make it the natural choice of knife makers. Hot rolled and annealed. Typical chemistry C 1.00, Mn .45, Si .30, CR 17.00, Mo .50.
A-2 TOOL STEEL
A fine grain, electric furnace air-hardening, 5% chrome oversize precision ground tool steel. It is a superior quality steel which has excellent wear and abrasion resistance properties. Typical chemistry C 1.00, Mn .60, Si .30, CR 5.20, Va .30, Mo 1.10
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