Per: huiqiang huang (The State Key Laboratory of Rolling and Automation, Northeastern University, No. 11, Lane 3, Wenhua Road, Heping District, Shenyang 110819, People’s Republic of China), hongshuang di (The State Key Laboratory of Rolling and Automation, Northeastern University, No. 11, Lane 3, Wenhua Road, Heping District, Shenyang 110819, People’s Republic of China), tianyu zhang (The State Key Laboratory of Rolling and Automation, Northeastern University, No. 11, Lane 3, Wenhua Road, Heping District, Shenyang 110819, People’s Republic of China), ning yan (The State Key Laboratory of Rolling and Automation, Northeastern University, No. 11, Lane 3, Wenhua Road, Heping District, Shenyang 110819, People’s Republic of China), jianping li (The State Key Laboratory of Rolling and Automation, Northeastern University, No. 11, Lane 3, Wenhua Road, Heping District, Shenyang 110819, People’s Republic of China)
Abstract:
A CMnSiAl transformation induced plasticity (TRIP) steel was used to study the effect of retained austenite on room-temperature mechanical properties. The steel plates with retained austenite were obtained by hot rolling, cold rolling and subsequent continuous annealing. The starting and finishing temperature of hot rolling are between Ac1 and Ac3. Reduction ratio of cold rolling is 75%. The continuous annealing is carried out at different intercritical temperatures. The relationship between work hardening exponent and retained austenite was discussed. The results show that, the Ac1 and Ac3 were much high because of the alloy elements, and the temperature range between them was wide. Due to the high hot rolling temperature, the grains was hereditarily refined as a result of dynamic recrystallization. Annealing at intercritical temperature of 930 ºC, retained austenite with relatively high stability reached a maximum volume fraction of 25%, a maximum total elongation of 30.2% and a best ultimate tensile strength × total elongation of 20.1 GPa•%. Instantaneous work hardening exponent reflects strengthening mechanisms at different strain stages. The TRIP effect of retained austenite is the main mechanism during deformation. With retained austenite of sufficient amount and high stability, continuous work hardening was observed in the tensile specimen of 930 ºC.
