不同应变速率下DP钢变形行为的微观机理研究

STUDY ON THE MICROSCOPIC DEFORMATION MECHANISM OF DP STEEL AT DIFFERENT STRAIN RATES

利用3 000 kN电子万能试验机和ZWICK HTM5020高速拉伸试验装置研究了双相钢（DP钢）在不同应变速率（10-4～600 s-1）下的拉伸变形行为,并结合XRD分析对双相钢组织中的位错密度进行了计算。结果表明,在准静态拉伸过程中,双相钢组织中的位错密度基本不变,其抗拉强度、断裂延伸率随应变速率变化也不明显;而在动态拉伸条件下,随着应变速率的增加,双相钢组织中的位错密度不断增加,抗拉强度也相应增加,塑性降低,最终导致能量吸收下降。

The mechanical response and the density of dislocation of dual-phase（ DP） steel at different strain-rate（ 10-4～600 s-1） were investigated by using a 3 000 kN universal material test machine and the high speed stretching device ZWICK HTM5020. Combined with XRD analysis,the dislocation density of DP steel was calculated. The results showed that under quasi-static tensile the dislocation density of DP steel was almost invariant and its tensile strength and fracture elongation did not change obviously with the increasing of strain rate. However,with further increasing of strain rate in dynamic tensile,the dislocation density increased,and the tensile strength of DP steel increased immediately,while the ductility decreased,which eventually led to the decline of the energy absorption.