Abstract
Carburized steels have large amount of internal stress near the surface, which will be defects when used. In order to decrease internal stress low temperature tempering (about 150∼200°) was used to be enployed after quenching. From the same point of view, induction surface hardened steels must be tempered at low temperature; however, the hardness of induction surface hardened steel decreases greater than with the conventional quenching.
Two reasons must be considered about this problem; the first is internal stress and the second is the metallurgical properties of rapid heated unstable martensite; however, the martensite of induction hardened sorbitic steels did not show any extraordinary softening at low temperature and the hardness change was nearly equal to the conventional quenching, and so the uniformity of martensite must have decided the stability of martensite.
In this paper the author described this problem.
