Investigation on the effects of parameters on hot cracking and tensile shear strength of overlap joint in laser welding dissimilar Al alloys

Abstract

With the increasing requirement for weight reduction in automotive industry, joining dissimilar aluminum (Al) alloys within overlap joint becomes more and more inevitable. However, hot cracking is a challenge issue in Al alloy welding. Overlap joint without hot cracking and also with good tensile shear strength is very important for industrial application. In order to better understand the hot cracking behavior in laser welding of dissimilar Al alloys, AA5754 and AA6013 sheets were overlap welded to investigate the effects of process parameters on hot cracking susceptibility, then the tensile shear tests were carried out on sound welded joint. The chemical composition, microstructure, and fusion ratio of welded joint were also studied. The results showed that the hot cracking can be prevented under appropriately choosing of welding process parameters. In particular, the critical process parameters to prevent the formation of hot cracking, i.e., welding speed 3.0, 3.3, 3.9, and 4.5 m/min with the corresponding overlap width 12, 10, 8, and 6 mm, were determined in the present study. The tensile shear strength of the sound welded joints without hot cracking reached 140 N/mm, which was qualified to meet the industrial application requirement.