Microstructural and mechanical properties examination of SS316L-Cu functionally graded material fabricated by wire arc additive manufacturing

In recent years, arc -based additive manufacturing techniques have been enthusiastically accepted for fabricating components made of various structural materials. In this work, a functionally graded material (FGM) structure of pure copper (Cu) and stainless steel (SS316L) was developed using cold metal transfer -based wire arc additive manufacturing (CMT-WAAM). Components combining Cu and steel show great usage in many industries since they combine high corrosion resistance, ductility, thermal conductivity, and wear resistance to the excellent mechanical properties. The CMT-WAAM fabricated FGM was well built and shows no deformation, bulging, and cracking in the graded region. Microstructural and elemental mapping analysis studies shows that Fe was deposited over Cu matrix in the gradient region and a gradual grain size and compositional gradient was observed. The phase analysis doesn't reveal formation on any metastable or intermetallic phase at the interface. The mechanical properties of the printed structure were analyzed by room temperature tensile testing, Charpy impact test and microhardness measurements in both scanning and build directions. The FGM samples show an average ultimate tensile strength of 641 +/- 10.06 MPa vs 427 +/- 5.03 MPa and elongation to fracture percentage of 19.8 +/- 1.13% vs 21.8 +/- 1.56% in scanning and build directions, respectively. The average Charpy toughness of fabricated FGM was 57.88 +/- 2.86 J vs 46.24 +/- 1.46 J in scanning and build directions, respectively. The tensile and impact strengths of FGM samples were higher than as fabricated pure Cu samples but lower than as fabricated SS316L samples and the fracture was dominated by ductile mode of fracture. The strength and ductility of CMT-WAAM fabricated SS316L-Cu FGM was significantly high and may allow use of these materials in engineering and industrial applications.