Influence of welding residual stress and welding method on fracture properties of welded joints

Abstract

To investigate the influence of residual stress on the fracture performance of T-joint welded joints in 6063 aluminum alloy, ABAQUS simulation was utilized to obtain the post-weld residual stress fields for different welding methods. A finite element model for toughness fracture of T-joints was established using the Johnson-Cook constitutive and damage models, aiming to analyze the impact of welding residual stress on fracture performance. The results indicate that under the same tensile rate, residual stress can lead to earlier fracture occurrence in the welded joints, thereby reducing the overall fracture performance. Among the different welding methods, the double-sided corner weld exhibits the best fracture performance, while the butt joint with a backing plate can effectively mitigate the influence of post-weld residual stress on fracture performance. Through the comparison of experiments and simulations, the material constitutive and damage parameters of each welding zone are verified, and the hardness test is carried out. The results indicate that the average hardness in the weld zone is approximately 63.8 HV, which is higher than the average hardness of 60.2 HV in the heat-affected zone. However, both the weld zone and the heat-affected zone have lower hardness values compared to the average hardness value of 81.5 HV in the base metal zone. Furthermore, it is observed that residual tensile stresses are predominantly distributed in the weld zone, which is one of the reasons contributing to the lower hardness at the center of the weld.