Dynamic recrystallization behavior and microstructural evolution in SPHC steel

Abstract

The dynamic recrystallization (DRX) behaviors in SPHC steel were investigated with hot compression tests at deformation temperatures of 950–1 150 °C, strain rates of 0.1–15 s−1, and initial austenite grain sizes of 86–232 μm. The effects of deformation temperature, strain, strain rate and the initial austenite grain size on the microstructural evolution during DRX were studied in detail. The results show that DRX is observed under the condition of the Zener-Hollomon parameter being less than 1.07×1013 s−1. The deformation activation energy for SPHC steel is calculated to be 299.4 kJ/mol by regression analysis. Austenite grain size of DRX is refined with decreasing temperature and increasing strain rate under steady state conditions, but it is not influenced by the initial grain size. The mathematical equation of DRX grain size of SPHC steel is obtained.