Resistance to softening during tempering of pearlitic and martensitic steels

Investigated are 40Kh4MBF, 40Kh4M1V3F, 50KhGSVF, 50KhGVF, and 15KhNMFA commercial steels. It is shown that the influence character of transformations taking place in carbide phase and in a solid solution of different steels (medium-alloy martensitic, low-alloy medium-carbon pearlitic and low-carbon low-alloy pearlitic) on their resistance to softening at tempering is the same (when process kinetics differs greatly). Steel softening at tempering is braked in such cases when, resulting from thermal treatment preceding long-term tempering, such carbide phase (type, distribution, dimensions) and such character of its interaction with solid solution are obtained which will be more stable under the following long-term heating