Fast in situ X-ray diffraction phase and stress analysis during complete heat treatment cycles of steel

This paper presents results obtained with a method for time and temperature resolved analysis of changes in phase composition and stresses/residual stresses during complete heat treatment cycles of steel, including quenching. Sample temperatures of up to 930 °C could be reached with a specially designed furnace, where fast cooling of the samples was realized by gas quenching. Measurements for phase and stress analysis could be performed with an acquisition rate of at least one value every 3 s. Results concerning residual stress relaxation during heating, and stress/residual stress development during quenching are presented and discussed for AISI E52100 ball bearing steel. The observed stress development during quenching followed the expected transformation behavior with some deviations that could be explained through the effects of surface decarburization. The system developed proved to be a suitable tool for characterizing phase and stress changes that occur during heat treatment of steels, as a function of time and temperature.