2017 Volume 56 Issue 6 Pages 340-344
The auto-tempering, which occurs during quenching, is an important issue in martensitic steels with carbon because it affects the mechanical properties of products. Therefore, from an engineering view point, it is required to evaluate quantitatively the degree of auto-tempering. In this study, the degree of auto-tempering was evaluated by the diffusion area of carbon which is calculated by the diffusion coefficient of carbon in bcc iron. As a result, it is found that the auto-tempering of martensite occurs markedly in the temperature range of 500-350°C during cooling, the rapid cooling more than 40°C/s is enough to suppress the auto-tempering as is same as the 200°C − 1 h tempering or less, and so on.
