Thermal stability investigation of expanded martensite

• Low temperature gas carburizing (LTGC) on the PH 17-4 and 13-8Mo stainless steels (St.St) and i.
• Investigation on the thermal stability of carburized layer were done.
• By increasing the time and temperature of heat treatment, deviation from Bragg’s angel and asymmetry of peaks decrease.
• Heating at upper time and temperatures, imerges other peaks of formed carbide (Fe3C).
• Heat treatment at 400°C & 450°C for 2 h are the Critical time and temperatures (CTT), for the application of carburized 13-8Mo and 17-4, respectively.

The aim of this work is to investigate thermal stability of expanded martensite. For this purpose, two martensitic stainless steels, PH 17-4 and 13-8Mo, were low temperature gas carburized. After heat treatment, it was found out that thermal stability of expanded layer of PH 17-4 is higher than that of PH 13-8Mo. Auger Electron Spectroscopy and microhardness machines were used to investigate carbon concentration and hardness of samples, respectively. X-ray diffraction was done to study crystal structures of samples before and after heat treatment.