PRODUCTION OF CARBURIZING HARDENING STEEL EXCELLENT IN DELAYED FRACTURE RESISTANCE

摘要

PURPOSE: To provide a carburizing hardening steel provided with desired surface hardness and excellent delayed fracture resistance by carburizing and hardening steel stock, tempering it in a specified high temp. range and thereafter executing induction hardening. ;CONSTITUTION: Steel stock is carburized and hardened, is thereafter tempered at 400 to 600°C and is furthermore subjected to induction hardening. By the above high temp. tempering, the diffusion and discharge of hydrogen intruding into the steel at the time of carburizing treatment and which easily generate delayed fracture can extremely easily be executed. As a result, the delayed fracture properties of the steel improves. Furthermore, by the tempering, the hardness of the carburizing layer decreases and wear resistance primarily required for the carburizing hardening steel deteriorates, but, by the subsequent induction hardening, it easily recovers to that of the carburizing layer or the value equal to that of the primary carburizing hardening steel for the second time.;COPYRIGHT: (C)1993,JPO&Japio