Design, testing and manufacturing of a metal–metal functionally graded material (SS316L-Cu) using wire arc additive manufacturing

Non-homogeneous composite materials also referred to as functionally graded materials (FGM) have become a subject of intense investigation in recent years. Fabrication of FGM allows combining various metals, metals with ceramic, various ceramics, polymers with metal and polymer with ceramic to obtain spatial variation in properties as a function of component dimension. This work contributes to this arena of research by reporting the development of a metal–metal FGM through the combination of copper and stainless steel utilizing cold metal transfer source based wire arc additive manufacturing as a novel route for scalable deposition to attain high thermo mechanical properties. Post-manufacturing characterization was done in the aspect of microstructure evolution, Techniques like digital image correlation (DIC) and X-ray diffraction techniques showed unique insights in the aspect of mechanical properties and crystalline properties. For instance, the copper-iron interface showed no metastable or intermetallic phase suggesting uniformity in the microstructure and while the mode of fracture of the FGM specimens showed ductile-fracture, crack emanation as a surface fissure nucleating from the interface of Cu-SS was evident. Moreover, estimates of thermal conductivity of the interface showed a value of ~ 164 (W/m–K) while thermal conductivity of the copper in the FGM was about ~ 220 W/m–K and that of steel was about ~ 30 W/m–K.