Changes in the microstructure of 13Cr-2Ni-2Mo stainless steels through the quenching process by induction heating

A 5 mm diameter shaft of 13Cr-2Ni-2Mo stainless steel was induction heated using a 15 mm diameter coil and subsequently quenched. The material’s microstructure before and after heat treatment were investigated by laser confocal scanning microscopy (LCM), X-ray diffraction (XRD) system, field emission scanning electron microscope (FE-SEM). The Vickers hardness distribution at the cross-section was measured. It was found that through the heat treatment process, the XRD pattern changed; the α-Fe peaks shifted and broadened. Grain boundaries as well as fine structures formed within grains were visible in the IH-hardened sample micrographs. This indicates the occurrence of martensitic transformation, resulting in an approximately two-fold hardness increase.