Experimental analysis and numerical simulation on residual stress and welding distortion of thin-gauge sheets for roof cover panel

Abstract In this work, the simulations and welding experiments including RSW and MIG processes for concave-convex distortion (CCD) defects of roof cover panel have been conducted. The detailed discussions on the temperature, residual stress, and formation mechanism as well as critical conditions are comprehensively analyzed. The welding simulation results have a satisfactory precision and reliability to match with the RSW and MIG experiments. The spread distance of residual stress in RSW decreases as the flange length increases. The spread distance of MIG process is slightly less than the minimum distance of RSW process at the flange length of 32 mm. Suppressing the presence of compressive stress is the key approaches to eliminate the CCD defects of outer roof cover panel. When the welding compressive stress exceeds the critical instability stress of outer roof cover panel, the partial buckling distortion indicates a dent CCD defect. In addition, there is a positive relationship between compressive stress and heat input power during MIG process. The magnitude of CCD defects become more and more serious with the increase of the bead length from 5 mm to 20 mm. The critical conditions to maintain an excellent appearance quality for RSW and MIG are the flange length of 27 mm to 35 mm and the bead length of 5 mm to 10 mm, respectively. The optimum MIG process with the bead length of 8 mm indicates an intact appearance quality of roof cover panel.