Analysis of residual stresses in electron beam welding with filler wire of Ti62A alloy

Residual stress significantly affects the performance of the welded joints and the tensile residual stress easily leads to the joint fracture and failure. A three dimensional nonlinear transient thermo-mechanically coupled finite element model of Ti62A alloy electron beam welding (EBW) with filler wire was established. The influence of the welding parameters, such as welding power, groove angles and number of welding layers on the temperature and residual stress evolutions was predicted and verified against existing literature data. The calculated results indicate that the high tensile stress of heat affected zone is very likely to induce the failure of the welded joints. When the welding power is 2600 W, the longitudinal residual stress along the welding direction is more symmetrical on both sides, and the force and deformation of the weldment will be more uniform. As the groove angle decreases, the transverse residual compressive stress on the joint surface becomes larger, which results in the low risk for cracking tendency of the joint. Increasing the number of welding layers reduces the weld reinforcement and the residual stress. In addition, the decline magnitude of residual stress decreases with the increase in the number of welding layers. Both the smaller groove angle and the multi-layer welding can effectively reduce the residual stress of weldments and improve the joint performance. The findings of this study will provide a good theoretical basis for optimizing welding process.