Martensitic graded quenching

Martensitic graded quenching: The steel is austenitized, and then immersed in a liquid medium (salt bath or alkali bath) with a temperature slightly higher or lower than the upper Martens point of the steel, kept for an appropriate time, and the inner and outer parts of the steel are treated. After the layer reaches the medium temperature, it is taken out for air cooling, and the supercooled austenite is slowly transformed into a quenching process of martensite. It is generally used for small workpieces with complex shapes and strict deformation requirements, and high-speed steel and high-alloy steel tools and dies are also commonly quenched by this method.