Dual-constricted plasma arc cladding of Inconel 625 alloy: arc characteristics, microstructure, and corrosion resistance

Abstract Inconel 625 alloy exhibits high strength, fabricability, and resistance to corrosion. Cladding processes including laser cladding, arc welding-based cladding, and plasma arc cladding have been applied to deposit the Inconel 625 layer with metallurgical bonding for surface protection. In this work, we developed a dual-constricted (DC) plasma arc cladding process to fabricate Inconel 625 coating. A numerical model was used to understand the arc thermal distribution, and the microstructure and corrosion resistance of the deposited layers were analyzed. It shows that in the DC plasma arc cladding process, the arc has a narrower column with increased energy density, and it can generate a higher arc pressure on the processing area. The deposited single track is narrower and thicker, and the melt pool penetration is deeper. In the Inconel 625 layer deposited by the DC-plasma arc, the microstructure is refined, and the Laves and MC precipitates are observed. The corrosion test indicates that the corrosion resistance in the 3.5% NaCl solution of the coating fabricated by DC plasma arc cladding is increased compared to conventional plasma arc cladding.