TRIP800钢点焊接头疲劳性能

Investigation on Fatigue Life of Spot-weld Jiont for TRIP800 Steel

对TRIP钢点焊接头进行了检验,在疲劳试验机上进行了疲劳试验,并对其焊点的疲劳失效进行了分析。结果表明:点焊接头经过外观检验和力学性能测试,满足相关标准和实际生产需要;TRIP钢点焊接头的疲劳极限为50MPa,疲劳裂纹源起始于热影响区高硬度淬火马氏体区与贝氏体、残余奥氏体高温回火最低硬度区的交接部位,并沿热影响区切线方向向两侧母材扩展;点焊接头疲劳断裂发生的区域硬度、强度较低,易发生塑性变形,从而引起较大的应力集中,且该区域处于处于应力较高区和拉伸-剪切复合应力区,使得疲劳裂纹易于形成、扩展。

The inspection of welded joint of TRIP steel was carried out. The fatigue test was carried out on fatigue test machine, and then, the fatigue failure of the solder joint was analyzed. The results show that： the spot welding joints through visual inspection and mechanical testing can meet the relevant standards and actual production needs. The fatigue limit of TRIP steel welded joints is 50 MPa.The fatigue crack initiates in the heat affected zone of the source of high hardness and quenched martensite area bainite,the residual austenite minimum tempering hardness zone transfer site, and along the tangential direction of the heat-affected zone, the fatigue crack extends to the sides of the base material. The regional hardness and strength of fatigue fracture of the spot welded joints is low, proning to plastic deformation, causing greater stress concentration, and the region is in a high stress area and stretch- composite shear stress area, which can make the formation of fatigue cracks easy to expand.