冷轧压下率和退火工艺对St37-2G结构用冷轧钢板组织和力学性能的影响

Effect of Cold Rolling Reduction Ratio and Annealing Process on Microstructure and Mechanical Properties of St37-2G Structural Cold-Rolled Steel Sheet

研究了冷轧压下率和退火工艺对St37-2G结构用冷轧钢板显微组织和力学性能的影响,并优化了生产工艺。结果表明:试验钢板经不同压下率冷轧并经670℃×5h退火后的显微组织均由铁素体、少量渗碳体和微量珠光体组成,仍保留着渗碳体沿轧向呈纤维状分布的特征;随着冷轧压下率的增大,试验钢板的硬度先增大后减小,在冷轧压下率60%时达到最大值;随退火升温速率的增大,试验钢板的屈服强度、抗拉强度以及塑性应变比明显下降,伸长率和加工硬化指数变化不大;最优的冷轧和退火工艺为冷轧压下率40%～50%,退火温度670℃,升温速率20℃·h-1。

The effect of cold rolling reduction ratio and annealing process on the microstructure and mechanical properties of St37-2G structural cold rolled steel sheet was studied and the production process was optimized. The results show that the microstructure of the tested steel sheet was composed of ferrite, a small number of cementite and marginala pearlite, and the characteristic of cenmentite distributing along rolling direction in the fibroid form was remained after the tested steel sheet was cold-rolled with different cold rolling reduction ratios and annealed at 670 ℃ for 5 h. The hardness of the tested steel sheet increased and then decreased with the increase of cold rolling reduction ratio, and the hardness showed maximum when the cold rolling reduction ratio was 60%. The yield strength, tensile strength and plastic strain ratio decreased obviously with the increase of heating rate during annealing, but the elongation and working hardening index changed a little. The optimal cold rolling and annealing process was as follows., the cold rolling reduction ratio of 40%- 50 %, annealing temperature of 670℃ and heating rate of 20 ℃· h^-1.