A comprehensive review on laser beam welding of dissimilar austenitic stainless steel to copper; process parameters, defects, microstructure and mechanical performance

Laser beam welding (LBW) process offers several advantages with high traverse speed and localized heating yields a narrow fusion zone (FZ) and smaller heat-affected zone (HAZ) in the weld bead. The LBW of dissimilar copper-austenitic stainless steel (Cu-ASS) joints have gained increasing attention for applications in energy systems, thermal management, and electrical applications due to the complementary mechanical, corrosion-resistant, and functional properties of these two materials. However, successful joining remains challenging due to the substantial differences in thermal conductivity, laser energy absorption, and melting behaviour, as well as the low mutual solubility between iron-copper (Fe-Cu), leading to weld defects and non-uniformity in microstructural characteristics. In the current study, recent developments in LBW of Cu-ASS joints are critically reviewed, focusing on how the key process parameters affect weld pool stability, microstructure, defect formation and mechanical properties. It also addresses the cause-effect relationships and mitigation strategies to minimize the defects associated with LBW of Cu-ASS joints such as porosity, incomplete fusion, solidification cracking and elemental segregation in welded components, and directly relates these to the melt flow behaviour of the molten pool. The effects of interlayers, especially Ni-based systems, beam oscillation, beam shaping, and shielding conditions on reducing metallurgical incompatibility and enhancing joint integrity are also reviewed. Additionally, this review also identifies future research directions to address existing gaps by systematically examining of scientific and publicly available literature on LBW of Cu-ASS joints, focussing on LBW reliability, development of robust process-microstructure-property relationships and enhancing the quality of weldments and its performance.