Martensitic stainless steel Martensitic stainless steel Martensitic stainless steel is a specific type of stainless steel alloy. Stainless steels may be classified by their crystalline structure into three main types: "austenitic", "ferritic" and "martensitic". Martensitic stainless steels can be high- or low-carbon steels built around the Type 410 composition of iron, 12% chromium, and up to 1.2% carbon. They are hardenable by heat treatment (specifically by quenching, or by quenching and tempering). The alloy composition, and the high cooling rate of quenching enable the formation of martensite. Tempered martensite gives steel good hardness and high toughness; used largely for medical tools (scalpels, razors
Martensitic stainless steel and internal clamps). Untempered martensite is low in toughness and therefore brittle. The characteristic body-centered tetragonal martensite microstructure was first observed by German microscopist Adolf Martens around 1890. In 1912, Elwood Haynes applied for a U.S. patent on a martensitic stainless steel alloy. This patent was not granted until 1919. Martensitic stainless steel can be nondestructively tested using the magnetic particle inspection method, unlike austenitic stainless steel. Also in 1912, Harry Brearley of the Brown-Firth research laboratory in Sheffield, England, while seeking a corrosion-resistant alloy for gun barrels, discovered and subsequently industrialized a martensitic stainless steel alloy. The discovery was