Austenite grain growth behavior of a GCr15 bearing steel cast billet in the homogenization heat treatment process

摘要

Isothermal homogenization heat treatments for a GCr15 bearing steel cast billet were performed at temperatures of 1000-1250 ℃ and holding times of 30-180 min. The grain size of austenite was measured with a metallographic microscope through the linear intercept method. Experimental results show that the grain size of austenite increases with the increase in heating temperature and holding time. The relationship between grain size and homogenization cycles was established. The homogeneity of the cast billet has an obvious effect on the austenite grain size distributions. Small and large grains were observed in the high- and low-concentration regions, respectively. The log-normal function can describe the grain size distributions more accurately than other functions after heating at low temperatures for short times. However, the Weibull function fits the grain size data well when the heating temperatures and holding times are improved.