焊接残余应力对高强钢点焊接头裂纹扩展及疲劳性能的影响  

EFFECT OF WELDING RESIDUAL STRESS ON CRACK PROPAGATION AND FATIGUE PERFORMANCE OF HIGH STRENGTH STEEL SPOT WELDING JOINT

作　　者：罗家元[1] 李鑫 谭超 LUO JiaYuan;LI Xin;TAN Chao(School of Mechanotronics and Vehicle Engineering,Chongqing Jiaotong University,Chongqing 400074,China)

机构地区：[1]重庆交通大学机电与车辆工程学院,重庆400074

出　　处：《机械强度》2024年第2期439-445,共7页Journal of Mechanical Strength

基　　金：重庆市技术创新与应用发展专项重点项目(cstc2021jscx-dxwtBX0022);重庆市博士后特别资助项目(Xm2017034);国家重点研发计划项目(2020YFF0404209)资助。

摘　　要：点焊接头因高度应力集中,极易于熔核边缘萌生疲劳裂纹,点焊产生的残余应力会影响其扩展。为探究点焊残余应力对疲劳裂纹扩展的影响规律,建立DP600高强钢点焊接头三维裂纹有限元仿真模型。基于热-弹塑性理论求解点焊残余应力场,在此基础上计算有无残余应力时折线裂纹的局部应力强度因子(Stress Intensity Factor,SIF)解,通过分析两种条件下裂纹最深点局部SIF随裂纹深度比变化的曲线,研究点焊残余应力对折线裂纹扩展的影响规律;基于断裂力学理论,采用改进的双参数模型预测有无残余应力时的疲劳寿命。结果表明,点焊残余应力使局部SIF显著提高,且随着裂纹深度比的增加,残余应力对其的影响程度也增加;考虑残余应力后裂纹整体扩展趋势不变但扩展速率显著增加,疲劳寿命由35616次下降至12564次。Due to the high stress concentration of spot welding joints,it is very easy to initiate fatigue cracks at the edge of the nugget,and the residual stress produced by spot welding will affect its propagation.To explore the influence of spot welding residual stress on fatigue crack propagation,a three⁃dimensional finite element simulation model of DP600 high strength steel spot welding joint was established.Based on the thermal⁃elastic⁃plastic theory,the residual stress field of spot welding was solved.On this basis,the local stress intensity factor(SIF)solution of the kinked crack with and without residual stress was calculated.By analyzing the variation curve of the local stress intensity factor at the deepest point of the crack with the crack depth ratio under the two conditions,the influence of residual stress of spot welding on the propagation of kinked crack was studied.Based on the fracture mechanics theory,the improved two⁃parameter model is used to predict the fatigue life with and without residual stress.The results show that the residual stress of spot welding significantly increases the local stress intensity factor,and the influence of residual stress on it increases with the increase of crack depth ratio.Considering the residual stress,the overall crack propagation trend remains unchanged but the propagation rate increases significantly,and the fatigue life decreases from 35616 times to 12564 times.

关 键 词：点焊残余应力 折线裂纹 应力强度因子 疲劳寿命 

分 类 号：TG405[金属学及工艺—焊接]