Joint Characteristics of Cu-Ni Alloy Fabricated by GTAW and MPAW Processes: A Comparative Study

The current work presents a comparative analysis of the joint behavior of Cu-Ni alloy weldments fabricated by Micro-Plasma Arc Welding (MPAW) and Gas Tungsten Arc Welding (GTAW) processes. The Cu-Ni alloy thin sheets are fabricated at different values of heat input (~40-135 J/mm) by MPAW and GTAW processes, respectively. Further, to evaluate their characteristics, joints are subjected to metallurgical, mechanical, and electrochemical testing. The joints fabricated with a higher magnitude of heat input resulted in deteriorated surface quality with a value of R ~ 6.13 µm. The increased surface roughness value of the joints resulted in a a higher corrosion rate (1.273 mm/year). A finer microstructural morphology is achieved for lower heat input condition. Accordingly, the weldment exhibited higher joint efficiency of ~91%.The prominent reason for achieving higher joint strength is related to the presence of lower secondary dendritic arm spacing (SDAS), which enhances the joint strength and ductility for the joints as compared to higher SDAS value. Further, the micro-fractography analysis reveals the presence of micro/macro-voids for high heat input, whereas the existence of numerous dimples of varying size and depth is observed for low heat input condition, implying the role of heat input of utmost importance.