Thermomechanical Processing without Accelerated Cooling to Achieve an As-Rolled Yield Strength of 400MPa in C-Mn Steel Plate

摘要

Thermomechanical (TM) rolling schedules have been developed using mathematical modelling, physical simulation and industrial trials to produce C-Mn steel plate with yield strengths of 400MPa and good impact toughness without the need of expensive micro-alloying additions or accelerated cooling. The process relies on careful selection of delay times to accumulate sufficient retained strain during austenite conditioning for enhanced nucleation of ferrite. An integrated heat transfer-austenite processing model was used to predict the final microstructure and mechanical properties. The extent of strain accumulation and progress of recrystallisation during rolling were confirmed by laboratory simulation. Based on these results, carefully controlled industrial TM rolling trials were performed on C-Mn steels. Adequate grain refinement and properties are achieved through suppression of recrystallisation and strain accumulation in the low austenite temperature region after a sufficient delay period prior to finishing.