Exploring hot deformation mechanism and precipitation behavior of Fe–5.6Mn–0.18C–1.1Al(–0.1Ti–0.22Mo) steels through physical modeling and microstructure characterization
Hongti Zhang, Hongyi Li, Nan Xiao, Steven Sun, Haile Yan, Minghui Cai, Young‐Kook Lee
Abstract
This study investigated the hot deformation mechanism and precipitation behavior of Fe–5.6Mn–0.18C–1.1Al(–0.1Ti–0.22Mo) steels through hot compression tests conducted at temperatures ranging from 750 °C to 1150 °C and strain rates from 0.01 s –1 to 1 s –1 . The flow stress behavior was analyzed using an Arrhenius–type constitutive equation, revealing that Ti–Mo microalloying increased the activation energy for hot deformation by 101.9 kJ/mol. Furthermore, the hot deformation behavior was modeled and predicted using the Bergström model for the work hardening/recovery stage and the Kolmogorov–Johnson–Mehl–Avrami (KJMA) model for dynamic recrystallization (DRX). Microstructural analysis of specimens deformed at 750 °C indicated that deformation–induced ferrite transformation (DIFT) facilitated softening in the intercritical region, with the Kurdjumov–Sachs (K–S) orientation relationship between the deformation–induced ferrite and the parent austenite. At 850 °C, nano–sized (Ti,Mo)C precipitates refined prior austenite grains and suppressed DRX due to a strong pinning effect. However, at 1050 °C and above, precipitate coarsening weakened the pinning effect, resulting in similar flow behavior and microstructural features in both steels.