Experimental Investigation and Numerical Simulation of Oscillating Laser–Ni Interlayer Welding of Dissimilar SS304/Al6061 Metals

This study investigates the oscillating laser welding of dissimilar SS304/Al6061 metals with a Ni interlayer, combining experimental analysis and numerical simulation. The results indicate that a laser power of 900 W yields optimal joint performance, achieving a maximum tensile-shear load of 1882 N. This performance overcomes the limitations of conventional non-oscillating welding, where uncontrolled heat input typically induces brittle failure. By regulating the interfacial thermal history, the oscillation process suppresses the extensive formation of brittle Fe–Al intermetallic compounds (IMCs) and facilitates the growth of the ductile Al_0.9Ni_1.1 phase. Fractographic analysis reveals a transition in fracture mode from mixed brittle–ductile to predominantly brittle as laser power increases. Furthermore, numerical simulations confirm that laser beam oscillation homogenizes the thermal field, thereby reducing spatial temperature gradients and mitigating localized overheating within the weld zone.