Martensitic stainless steel: stainless steel whose mechanical properties can be adjusted by heat treatment. In layman's terms, it is a kind of hardenable stainless steel. Typical grades are Cr13 type, such as 20Cr13, 30Cr13, 40Cr13, etc. After quenching, the hardness is relatively high, and different tempering temperatures have different strength and toughness combinations. It is mainly used for steam turbine blades, tableware, and surgical instruments. According to the difference in chemical composition, martensitic
stainless steel can be divided into martensitic chromium steel and martensitic chromium-nickel steel. According to the different structure and strengthening mechanism, it can be divided into martensitic stainless steel, martensitic and semi-austenitic (or semi-martensitic) precipitation hardening stainless steel and maraging stainless steel.