RESEARCH ON THE DELAY-QUENCHING OF THE INDUCTION SURFACE-HARDENING

Abstract

General process of the induction surface hardening is as follows: a steel specimen of which the surface is austenitized with induction heating is used to be quenched in the water-jet, as soon as the heating has been stopped. If the quenching time is delayed after the induction heating, hardness of the specimen is not lowered than that of the instantanusly quenched specimen, this unsoftening condition of delay-time is amounted to several seconds for medium-carbon steel, and scores seconds for low alloy steels with medium-carbon content.
This special quenching method above described is called as a "delay-quenching", and it takes effect to the stress relief on the induction surface-hardening.
In the former report it was verified that a "stop-quenching", was a good application for the purpose of stress relief on the induction surface-hardening. However, it cannot be applied to the continuons induction hardening of a long steel rod, on the contrary, "delayquenching" can be applied to the continuous induction hardening.