Microstructure and mechanical properties of wire arc additive manufactured bi-metallic structure

Abstract

Wire arc additive manufacturing (WAAM) with better material utilisation efficiency and higher deposition rate was employed to fabricate bi-metallic structure (BMS) of non-stabilised austenitic stainless steel (SS904L), and solid solution strengthened Hastelloy C-276. The micrographs confirmed the existence of directionally elongated, columnar, and equi-axed dendrites in the BMS. Significant grain coarsening was observed in the re-melted layers. The tensile properties of Hastelloy C-276 and SS904L were comparable with wrought counterparts, while the bi-metallic interface sample fractured in the SS904L side. The presence of secondary phases and varying microstructure along the building direction is responsible for the anisotropy in mechanical properties. Microhardness results revealed the steep increase at the bi-metallic interface due to the dilution of elements between two materials.