Investigation of mechanical and corrosion behavior of multi-pass nickel-aluminum bronze fabricated through wire-arc directed energy deposition

In this study, a multi-pass nickel-aluminum bronze (NAB) layer was deposited on a steel surface by wire-arc directed energy deposition (DED). The study then comparatively analyzed the microstructural characterization, mechanical properties, and corrosion behaviors of the overlap region between adjacent passes and the substrate (NAB layer). The results revealed that the grain size of the previous deposited layer in the overlap region was smaller than that of the post deposited layer and that the precipitated phase was mainly a lamellar xIII phase. Based on the microstructural differences, the strength of the overlap region was approximately 100 MPa less than that of the substrate. However, following double-layer deposition, the strength of the overlap region increased significantly and was nearly equivalent to that of the substrate, reaching 730 MPa. The corrosion of the multi-pass wire-arc DED of the NAB alloy was divided into two stages. Initially, because of the small grain size and the presence of the eutectic organization xIII and a-Cu phases, the corrosion susceptibility in the overlap region was higher than that of the substrate. After the corrosion product film was formed, the strength and bonding force with the alloy of the corrosion product film on the overlap region were better than those on the substrate, and the corrosive resistance of the overlap region was greater than that of the substrate.