Mathematical models for predicting the austenite grain size in hot working of GCr15 steel

The objective of this study is to develop a set of mathematical models which can predict the austenite grain size of GCr15 steel in hot working process. The models can describe the evolution of grain size during dynamic recrystallization (DRX), metadynamic recrystallization (MDRX), static recrystallization (SRX), and grain growth process after recrystallization, respectively. The DRX behavior in GCr15 steel was investigated by the single hot compression tests, and the double compression tests with different inter-stage delay times were used to research the kinetics of MDRX and SRX. The tests were performed on the Gleeble-3800 thermo-mechanical simulation machine at temperature from 950 to 1150 °C, strain rate from 0.01 to 50 s−1 and initial austenite grain size from 26.3 to 90.0 μm. In addition, a set of specimens were heated to 950, 1050, 1100 and 1150 °C for 0–480 s to determine the grain growth model after recrystallization. The predicted results of grain size are in good agreement with the measured ones.