Comparative study on additive manufacturing of bi-metallic functional graded materials via robotic double-pulse and plasma arc welding

In order to improve the durability, high temperature corrosion resistance and strength of SS316L in industrial applications, IN625 is used as an efficient and expensive covering material. In this paper, SS316L/IN625 thin-walled functionally graded materials with a gradient of 5% were prepared by twin-pulse MIG welding and plasma welding. The results showed that both samples exhibited well morphology and no macroscopic defects were observed. The deposition process was stable and the surface roughness was less than 4%. Furthermore, SEM and EDS analysis showed that the microstructure of the deposited samples was columnar and exhibited epitaxial growth. The microcrack was not observed in the 67% SS316L region, and the hardness and horizontal tensile properties of two samples showed an increasing tendency from the baseplate to the top, and their total average values were approximately the same. Moreover, the samples obtained by two different processes with the same gradient had similar properties and no obvious anisotropy, and the tensile fracture of the two samples showed typical ductile fracture characteristics. This study provides the theoretical basis and reference value for arc additive manufacturing gradient materials.