汽车用高强度钢板的动态变形行为
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摘要
对DP590钢板和CR340LA钢板在应变速率为0.003s-1(准静态)和20~700s-1(动态)下进行了室温拉伸试验,研究了试验钢板的动态拉伸变形行为、应变速率敏感性和动态断裂行为。结果表明:两种试验钢板的动态真应力-真应变曲线均无屈服平台,屈服后真应力随真应变的增加先快速增大后缓慢增大;应变速率对屈服强度的影响略高于对抗拉强度的影响,并且DP590钢板的应变速率敏感性和硬化指数均高于CR340LA钢板的;两种试验钢板的均匀伸长率均随应变速率的增加而降低;随应变速率的增加,DP590钢板中的位错密度增加,当应变速率不小于200s-1时出现位错胞;DP590钢板在准静态拉伸时发生明显颈缩,而动态拉伸时未发生颈缩,且随应变速率的增加,拉伸断口上的C形韧窝数量减少,等轴状韧窝数量增加。
The room temperature tension tests at strain rates of 0.003 s-1(quasi-static)and 20-700 s-1(dynamic)were conducted on DP590 steel sheet and CR340 LA steel sheet,and then the dynamic tensile deformation behaviour,strain rate sensitivity and dynamic fracture behaviour of tested steel sheets were studied.The results show that no yield platforms were observed on the dynamic true stress-true strain curves of the two tested steel sheets.After yield,the true stress increased rapidly and then slowly with increasing true strain.The effect of strain rate on yield strength was bigger than that on tensile strength,and the strain rate sensitivity and hardening coefficient of DP590 steel sheet were higher than those of CR340 LA steel sheet.The uniform elongation of the two tested steel sheets decreased with strain rate increasing.With increasing strain rate,the dislocation density in DP590 steel sheet increased,and dislocation cells formed at strain rate no less than 200 s-1.Obvious necking occurred during quasi-static stretching of DP590 steel sheet,while no necking occurred during dynamic stretching.With increasing strain rate,the amount of C-shaped dimples on the tensile fracture of DP590 steel sheet decreased,and the amount of equiaxed dimples increased.
The room temperature tension tests at strain rates of 0.003 s-1(quasi-static)and 20-700 s-1(dynamic)were conducted on DP590 steel sheet and CR340 LA steel sheet,and then the dynamic tensile deformation behaviour,strain rate sensitivity and dynamic fracture behaviour of tested steel sheets were studied.The results show that no yield platforms were observed on the dynamic true stress-true strain curves of the two tested steel sheets.After yield,the true stress increased rapidly and then slowly with increasing true strain.The effect of strain rate on yield strength was bigger than that on tensile strength,and the strain rate sensitivity and hardening coefficient of DP590 steel sheet were higher than those of CR340 LA steel sheet.The uniform elongation of the two tested steel sheets decreased with strain rate increasing.With increasing strain rate,the dislocation density in DP590 steel sheet increased,and dislocation cells formed at strain rate no less than 200 s-1.Obvious necking occurred during quasi-static stretching of DP590 steel sheet,while no necking occurred during dynamic stretching.With increasing strain rate,the amount of C-shaped dimples on the tensile fracture of DP590 steel sheet decreased,and the amount of equiaxed dimples increased.
引文
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[15]蔡恒君,胡靖帆,宋仁伯,等.800 MPa级冷轧双相钢的动态变形行为及本构模型[J].工程科学学报,2016,38(2):213-222.
[2]王学双,曹广祥,张义,等.DP780钢应变率敏感特性研究及本构方程的建立[J].汽车工艺与材料,2014(3):48-51.
[3]王学双,庄华晔,曹广祥.汽车用先进高强钢动态力学行为研究[J].汽车工艺与材料,2015(9):35-39.
[4]姚贵升.车身用钢板的抗碰撞性能[J].汽车工艺与材料,2006(8):15-18.
[5]代启锋,宋仁伯,关小霞.超高强铁素体-马氏体双相钢在动态拉伸变形条件下组织和性能研究[J].材料工程,2013(4):6-10.
[6]田文扬,刘奋,韦春华,等.DP980高强钢动态拉伸力学行为[J].材料工程,2017,45(3):47-53.
[7]孟宪明,谢书港,方锐,等.B340-590DP双相高强钢板的动态变形行为[J].钢铁研究学报,2015,27(6):51-55.
[8]余海东,郭永进.双相钢DP600塑性率相关效应试验及本构模型[J].上海交通大学学报,2009(10):1672-1675.
[9]YU H D,GUO Y J,LAI X M.Rate-dependent behavior and constitutive model of DP600steel at strain rate from 10-4 to103 s-1[J].Materials and Design,2009,30(7):2501-2505.
[10]张赛,孟庆振,谢书港,等.B250P1低合金钢的动态力学行为及其本构模型[J].理化检验-物理分册,2016,52(6):370-383.
[11]何平,陈浩铭.基于高速拉伸试验的车身用钢板材料应变速率敏感特性研究[J].汽车技术,2010(7):39-42.
[12]宋维锡.金属学[M].北京:冶金工业出版社,1980:405-414.
[13]WINTHER G,JENSEN D J,HANSEN N.Dense dislocation walls and microbands aligned with slip planes:Theoretical considerations[J].Acta Materialia,2015,45(12):5059-5068.
[14]代启锋,宋仁伯,范午言,等.DP1180双相钢在高应变速率变形条件下应变硬化行为及机制[J].金属学报,2012,48(10):1160-1165.
[15]蔡恒君,胡靖帆,宋仁伯,等.800 MPa级冷轧双相钢的动态变形行为及本构模型[J].工程科学学报,2016,38(2):213-222.