Underwater wet laser cladding Ni80Cr20- x wt%Nb (x = 0, 10) coating: Metallurgical forming, microstructure and corrosion behavior

Underwater wet laser cladding technology (UWLC) will play a crucial role in the emergency repair of marine engineering equipment. The existence of water environment makes the UWLC process face more challenges. Therefore, it is meaningful to develop materials suitable for underwater wet laser cladding. Considering the special demands of UWLC coatings for corrosion resistance, Ni, Cr and Nb elements with excellent corrosion resistance were selected as the main components. In this article, Ni80Cr20-x wt% Nb (x = 0, 10) coatings were successfully prepared by UWLC. The forming process of Ni80Cr20-x wt% Nb (x = 0, 10) coatings in water environment were studied. The corrosion resistance, corrosion morphology and elemental valence of Ni80Cr20-x wt% Nb (x = 0, 10) coatings were studied. The results shown that Ni80Cr20-x wt% Nb (x = 0, 10) coatings were well formed, with excellent metallurgical bonding between the coating and substrate. The addition of Nb element resulted in the transition of the single solid solution (FCC) into the dual-phase solid solution (FCC and Laves) of Ni80Cr20-10 wt% Nb UWLC coating. Furthermore, Ni80Cr20-10 wt% Nb UWLC coating exhibited higher selfetching potential, lower self-etching current density and higher critical point corrosion potential, indicating excellent anti-corrosion properties. The composition design of the underwater cladding coatings, which combined good formability and excellent corrosion resistance, has significant implications for improving of underwater repair quality.