1988 Volume 74 Issue 2 Pages 342-349
It was clearly shown in the previous paper that Induction Heating Tempering (IHT) showed an independent effect on strengthening and toughening of Si-Cr spring steel (SUP12) apart from the effect of grain refining by Induction Heating austenitizing and Quenching (IHQ).
So, in order to clarify the cause of the effect of IHT on strengthening and toughening the micro-structureof IHT and Furnace Heating Tempered (FHT) materials was investigated. The results are as follows :
(1) The amount of grain boundary precipitation of carbide in IHT material is slightly less than that in FHT material. And in the case of comparatively higher hardness material such as HRC=53, carbide particle in IHT material is smaller than that in FHT material.
(2) These characteristics of micro-structure coincided with consideration about the mechanical properties, the nucleation and growth process of austenite from tempered structure, and the calculation results about carbide precipitation.
(3) Retained austenite in IHT material is also effective for strengthening and toughening, but the effect is less than that of carbide precipitation.
