钛合金窄间隙TIG焊试板热处理前后表面残余应力研究

Surface Welding Residual Stresses of TC4 Ti-Alloy Weldments by Narrow Gap TIG Welding Before and After PWHT

采用磁控窄间隙TIG焊接方法对31mm厚TC4钛合金试板进行焊接,焊接完成后采用压痕应变法测量真空退火处理前后表面焊接残余应力分布。结果表明,试板表面纵向焊接残余应力σx和横向焊接残余应力σy均较高;试板下表面焊接残余应力高于上表面焊接残余应力;峰值焊接残余应力出现在高温热影响区,数值可以达到材料屈服强度的50%~60%。经过650℃的真空退火热处理,焊接试板的纵向和横向残余应力均显著降低,残余应力降低幅度最高超过50%,剩余残余应力峰值均低于200MPa,表面残余应力重新分布。

31mm thick TC4 Ti-alloy plates were welded by magnetically controlled narrow gap TIG,the surface residual stress distributions were measured by indentation strain-gage method before and after vacuum post-welding heat treatment(PWHT).The results show that the levels of longitudinal and transverse residual stress is all high on the weldment surface.The residual stresses on the lower surface are little higher than that on the upper surface,especially for transverse residual stress.The residual stresses peak value of the weldment exists in the high temperature heat affect zone,which reaches 50%-60%of the material yield strength.After 650°C vacuum post-welding heat treatment,longitudinal and transverse stresses on the weldment surface are significantly reduced,maximum stress reduction is more than 50%,the residual stress peak value left on the surface doesn’t exceed 200MPa,and the original welding residual stresses on the surface go to redistribute.