Influence of overlap laser welding parameters on the mechanical and microstructural properties of AISI 1018 and 301LN stainless steel joints

This study investigates the impact of laser overlap welding parameters on the mechanical and microstructural properties of dissimilar joints between AISI 1018 low-carbon steel and stainless steel 301LN. A series of experiments were conducted varying laser power, travel speed, and oscillation amplitude to determine optimal welding conditions. Tensile tests revealed that the welds exhibited significantly different strengths and displacements, with the optimal parameters achieving a maximum load of 39.6 kN and a displacement of 9.3 mm. Macrostructural analysis indicated that higher oscillation amplitudes resulted in broader but shallower welds, whereas lower amplitudes achieved deeper penetration. Microstructural examination showed varied phase formations, including martensite and bainite, influenced by the diffusion of alloying elements such as chromium and nickel. The formation of chromium carbides significantly enhanced the hardness of the fusion zone, with microhardness values reaching up to 470 HV at moderate penetration. Fractographic analysis of tensile-tested samples highlighted different fracture mechanisms, with optimal welds fracturing in the base material rather than the weld interface, indicating superior joint strength. This study provides critical insights into optimizing laser overlap welding parameters to enhance the mechanical performance and structural integrity of dissimilar metal joints, contributing to improved industrial welding practices.