SPCC冷轧钢等温退火的微观组织和力学性能

Microstructure and Mechanical Properties of SPCC Cold-rolled Steel with Isothermal Annealing

在Gleeble-1500D热模拟机上,对SPCC冷轧钢进行等温退火试验和力学性能测试。分析了不同退火温度和保温时间对SPCC冷轧钢组织和性能的影响,建立了等温退火工艺参数与SPCC冷轧钢板力学性能间的数学模型。研究结果表明：退火温度低于550℃时,只发生铁素体回复;650~850℃时,发生铁素体的再结晶及晶粒长大。屈服强度和抗拉强度随退火温度升高而降低,在650℃时大幅度下降,850℃时达到最低。同样退火温度下,屈服强度和抗拉强度随保温时间增加先下降后趋于稳定。采用加权平均法建立SPCC冷轧钢力学性能模型,并对模型进行了验证。屈服强度、抗拉强度和伸长率的平均绝对误差分别为20.2 MPa、23.2 MPa和1.4%,平均相对误差分别为3.9%、4.3%和10.7%,证明模型具有较高的精度。

Both the isothermal annealing experiment and mechanical properties test of SPCC cold-rolled steel were carried out via thermal mechanical physical simulator Gleeble1500 D. The effects of isothermal annealing temperature and time on the SPCC cold-rolled steel microstructure and mechanical properties were explored.Mathematical model of the mechanical properties of the steel with annealing parameters was established. The results show that ferrite recovery only occurs at annealing temperature less than 550 ℃,and ferrite recrystallization and grain growth happen between 650 ℃ and 850 ℃. The yield strength and ultimate strength of the steel decrease as temperature elevates,the descent speed is very fast at 650 ℃,and both strengths are lowest at 850 ℃. While at the same temperature,the yield strength and ultimat strength decrease as soak time increases and finally tend to be stable. The mechanical properties model of SPCC cold-rolled stell based on weighted average method was established and validated. The model absolute errors of the yield strength,the ultimate strength and the elongation are 20. 2 MPa,23. 2 MPa and 1. 4% respectively. The model relative errors of them are 3. 9%,4. 3% and 10. 7% separately. That means the mathematic models have better accuracy.