The Effects of the Variable-Pressure Rolling of a Wire Arc Additively Manufactured Inconel625-SS308L Bimetallic Structure

Abstract

The superior deposition rates of Wire Arc Additive Manufacturing (WAAM) allow for the production of a substantial number of parts while reducing the time and cost associated with machining, and have attracted significant attention. This study focused the microstructural and mechanical properties of a bimetallic thin-wall composed of SS308L and Inconel625, manufactured using variable-pressure rolling WAAM. A detailed analysis of the cross-sectional microstructure of the bi-metallic wall of non-pressure cases revealed a columnar solidification structure. In contrast, the pressured case was dominated by equiaxed structures. The microhardness tests conducted on the bimetallic interface revealed a hardness range of 139–188 HV within the SS308L region, and a 187–222 HV hardness spectrum within the Inconel625 region. The bimetallic interface displayed no unexpected hardness variations. Tensile tests carried out in the vertical direction across the bi-metallic interface resulted in a localized failure at the 308L region. The range of ultimate tensile strength was between 539 and 585 MPa, the yield strength varied from 344 to 377 MPa, and the elongation measurements were found to be within the range of 37 to 44%. All test specimens showed a consistent pattern of ductile rupture upon fractographic inspection, with fracture occurring in the SS308L region.