Laser Overlapping Welding Technology of Aluminum/Steel with Prefabricated Copper Coating

This research investigates an advanced method for improving aluminum-steel weld joints using pulsed laser lap welding with prefabricated copper interlayers. As lightweight high-strength structures are increasingly needed in automotive and aerospace applications joining dissimilar metals like aluminum and steel poses challenges due to brittle intermetallic compound (IMC) formation and thermal mismatches.By applying electrochemical deposition of copper and optimizing pulsed laser parameters-such as energy duration and frequency-this study examines how copper interlayers influence weld quality. Experiments with 6061 aluminum and DP590 dual-phase steel show that copper coatings act as diffusion barriers reducing the formation of brittle Fe-Al IMCs and promoting more ductile Al-Cu and Cu-Fe phases.Comprehensive evaluations including tensile-shear testing microhardness mapping SEM TEM EDS corrosion testing and COMSOL thermal simulation confirmed improved weld strength and corrosion resistance. Under optimal conditions (60.2 μm Cu layer 10 J energy 6 ms duration 16 Hz) the joint achieved a tensile strength of 59.8 MPa with enhanced durability.The results provide a solid foundation for developing reliable dissimilar metal joining techniques offering practical solutions for next-generation lightweight engineering structures.