Martensitic stainless steel

The name given to a structure that results when chromium (in the lower ranges 12 to 17%) and carbon (around 0.15%) is added to iron. This structure can be “heat treated” to high hardness levels and is sometimes called “hardenable stainless” 400 series of which 410, 420 and 440 (very high carbon levels between 0.60 and 1.20 %) are the most common.