Analysis of Hot Ductility and Grain Growth Behavior in High‐Manganese Cryogenic Steel

Transverse cracking during continuous casting and subsequent hot working remains a major obstacle to the industrial application of high‐Mn steels. This study demonstrates that the hot workability of an industrial 0.45C–24Mn–3Cr steel is governed by the combined effects of reheating temperature, deformation temperature, dynamic recrystallization (DRX), and grain‐boundary stability. The experimental results demonstrate that lowering the reheating temperature effectively improves hot workability, mitigates damage to the austenite grains, and suppresses abnormal grain growth. Specimens reheated at 1130 °C exhibited higher and more stable hot ductility than those reheated at 1300 °C. A Region II ductility trough occurred at 700–900 °C because of incomplete DRX, strain localization, and limited grain‐boundary accommodation, whereas pronounced DRX, grain refinement, and annealing‐twin formation restored ductility at 900–1100 °C, with the maximum reduction of area obtained near 1000 °C. Reheating at 1300 °C accelerated grain‐boundary migration and DRX but simultaneously weakened austenite grain boundaries, promoted localized melting and void formation at high deformation temperatures, and eventually triggered abnormal austenite grain growth. Thermodynamic analysis further showed that Cr stabilizes austenite but also increases the tendency for Cr‐rich M ₂₃ C ₆ precipitation in the intermediate‐temperature range. Reheating near 1130 °C is therefore recommended to reduce abnormal grain growth and surface‐cracking susceptibility.