Microstructural evolution and mechanical performance of laser welded similar and dissimilar joints of inconel 718 and AISI 416 stainless steel

This study adopts laser beam welding to investigate the welding performance of Inconel 718 superalloy plates and AISI 416 stainless steel plates, both 3 mm thick. Three joint configurations were investigated, comprising similar Inconel 718–Inconel 718 and AISI 416–AISI 416 joints, along with a dissimilar Inconel 718–AISI 416 joint. Multi-dimensional property characterization was carried out via macro and micro structure observation, tensile testing, Vickers microhardness testing, and fracture analysis. Tests found that the three types of joints differ in their microstructures, tensile properties, hardness distribution, and fracture modes. Among the three joint configurations, the dissimilar Inconel 718–AISI 416 joint exhibited the highest tensile strength, with a UTS of 695 MPa and a YS of 538 MPa, while the Inconel 718–Inconel 718 joint showed the highest elongation of 15.4%. The AISI 416–AISI 416 joint exhibited a UTS of 527 MPa and an elongation of 11.2%. The differences in mechanical response are associated with the distinct microstructural characteristics and material interactions developed during laser welding. The results demonstrate that laser beam welding can produce sound joints in both similar and dissimilar material combinations, with the resulting mechanical behaviour depending on the material combination and microstructural evolution within the welded region.