双相钢拼焊板温拉伸流变应力研究

Flow Stress of Dual Phase Steel Tailor Welded Blanks during Warm Tensile

采用CMT5205微机控制电子万能试验机对B340/590DP双相钢母材及拼焊板进行温拉伸试验,研究母材及拼焊板在变形温度为550～700℃、应变率为0.000 1～0.1 s–1条件下的流变应力行为。采用等应变法计算获得焊接区应力-应变曲线,通过改进后的含软化因子模型分别建立母材和焊接区材料的流变应力模型,并验证流变应力模型的准确性。结果表明,双相钢母材及拼焊板在温拉伸试验中发生了明显的动态回复与动态再结晶,流变应力随变形温度的升高而降低,随应变率的增加而增加;流变应力的预测值与试验值吻合较好,具有较高的可信度。

Warm tensile tests of B340/590DP dual phase steel and tailor welded blanks（TWBs） are carried out by using the testing machine CMT5205.The flow stress behaviors of base metal and TWBs are investigated in the temperatures range form 550 ℃ to 700 ℃ and strain rates from 0.000 1 s-1 to 0.1 s-1.Stress-strain curves for welding zone are obtained by calculation of equal jigging strain method.The models of base metal and tailor welded blanks are established by the improved model contained softening factor.The results show that the dynamic recovery and dynamic recrystallization occur obviously during warm tensile tests of base metal and TWBs.The flow stress increases with the increase of strain rates and decreases with the increase of temperature.The flow stress predicted by the proposed models well agrees with experimental results,which is reliable.