含Al双相钢相变行为及退火温度对力学性能的影响

Phase transformation behavior and influence of annealing temperature on mechanical properties of Al-containing DP steel

利用Formastor热膨胀仪测试了一种含Al中硅中锰双相钢的连续冷却过程的相变行为,采用连续退火热模拟试验机进行了连续退火试验,测试了力学性能,观察了微观组织。结果表明,试验钢以10℃/s的加热速率加热过程中,Ac1和Ac3分别为713℃和918℃,与热力学平衡状态相比,分别需要29℃和58℃的过热度;连续冷却过程中,发生铁素体相变的临界冷速为3～5℃/s之间,贝氏体相变的临界冷速为15～30℃/s;连续退火过程中,随淬火温度的提高,抗拉强度呈逐渐升高的趋势,而伸长率呈逐渐降低的趋势,应变硬化指数n值对淬火温度不敏感。

Transformation behavior of continuous cooling process on Al-containing medium-manganese-silicon DP steel was investigated by Formastor thermal dilatometer,and the continuous annealing process was simulated by continuous annealing equipment. The mechanical properties was tested and the microstructure was observed. The results indicate that the Ac1 and Ac3are 713 ℃ and 918 ℃ respectively when the heating rate is 10 ℃/s,and the degree of superheat are 29 ℃ and 58 ℃ respectively compared to the thermodynamic equilibrium state.The critical cooling rate of ferrite transformation and bainite transformation are 3-5 ℃/s and 15-30 ℃/s respectively. The tensile strength increases with the increase of quenching temperature,and the elongation shows the opposite trend. The n-value is not sensitive to the quenching temperature.