An improved simulation of the residual stress field in the VPPA-MIG hybrid welding of high-strength aluminum alloy

• A softening model for aluminum alloy materials was established for the welding process of high-strength aluminum alloys. • The research found that the softening behavior of the aluminum alloy welding joint reduced the residual stress in the stress concentration areas on both sides of the weld seam. • Research has shown that using aluminum alloy materials to soften the model can accurately predict the residual stress of aluminum alloy welded structures. The research results provide a theoretical basis for enhancing the service reliability of aluminum alloy welded structures in industries such as aerospace and automotive manufacturing. Accurate analysis of residual stress in aluminum alloy welds is essential for ensuring the quality and service life of joints. The mechanical properties of both as-received and softened high-strength aluminum alloy at different temperatures were determined at various temperatures through high-temperature tensile experiments on 11 mm-thick 7A52 plates. Furthermore, a material softening model for aluminum alloy was developed based on Lifshitz-Slyozov-Wagner (LSW) theory. The impact of weld joint softening on residual stress was investigated through VPPA–MIG hybrid welding simulations, with the results derived from the proposed softening model evaluated against a conventional modeling approach. The softening model predicts significantly lower residual stresses in the heat-affected zone (HAZ) adjacent to the weld, with maximum longitudinal and transverse tensile stresses reduced by 26.4 % and 25.2 %, respectively, while stresses outside the HAZ remain comparable to the conventional model. X-ray diffraction validation demonstrated closer agreement with the softening model’s predictions. The developed model accurately predicts residual stress distributions in aluminum alloy welds, supporting improved service reliability, process optimization, and structural integrity assessment in aerospace and automotive applications.