440A

440A is a martensitic stainless steel grade in the 440 series, produced for applications that require corrosion resistance combined with the ability to be hardened. It typically contains about 16 to 18 percent chromium and a relatively low carbon content of roughly 0.65 to 0.75 percent, with manganese and silicon as minor alloying elements. The lower carbon content means 440A can achieve moderate hardness but will not reach the high hardness levels of higher‑carbon grades like 440C.

Properties of 440A include good corrosion resistance for a hardened steel, along with the ability to take a sharp edge and provide reasonable toughness. After appropriate heat treatment, it can be hardened to mid‑range hardness on the Rockwell scale, with the exact value depending on tempering. The grade is often noted for being easier to machine and grind than higher‑carbon martensitic grades, while still offering adequate wear resistance for many everyday uses.

Heat treatment typically involves heating to form the martensitic structure (austenitizing), followed by quenching and tempering to the desired hardness. The process parameters vary, but the aim is to balance hardness, wear resistance, and toughness suitable for the intended end use.

Common applications include budget to mid‑range knife blades and other tool components where corrosion resistance is important and extreme wear resistance is not required. 440A is also used in some scissors, blades, and certain stamped knife parts, reflecting its role as a versatile, cost‑effective stainless steel option.