Finite Element Analysis of Restraint Intensities and Welding Residual Stresses in the Ti80 T-Joints

Abstract

The restraint intensity of Ti80 T-joints was investigated using finite element analyses. The influence of slit height, vertical plate thickness and base plate thickness was studied, respectively. Results show that the slit height and vertical plate thickness have a significant impact, while the effect of base plate thickness is negligible. A prediction model of restraint intensity was constructed through binary linear regression; the error was estimated at about 10%. Then, finite element simulations were carried out to study the welding residual stresses of specimens with different restraint intensities. The results show that residual stresses on the backing weld surface are higher in the middle and lower at both ends, while the weld root shows opposite results. In general, stresses at the weld root are greater than those on the weld surface. The mean value of the residual stress at the weld root increases with the increase in restraint intensity but not uniformly, i.e., it is slow at first and then it increases rapidly. A prediction model of the residual stress was produced through cubic fitting, and the errors between the finite element simulations and predictions were about 8%. Using the prediction model, the residual stress of actual Ti80 alloy workpieces can be estimated before welding, and a corresponding strategy for avoiding cracks can be generated.