Comparison of Fe30Co20Cr20Ni20Mo3.5 High Entropy Alloy Coatings Prepared Using Plasma Cladding, High-Speed Laser Cladding, and Deep Laser Cladding

Three kinds of Fe30Ni20Co20Cr20Mo3.5 high entropy alloy (HEA) coatings were prepared on the surface of a Q235 steel plate using plasma cladding and laser cladding. The microstructure, crystal structure, element distribution, microhardness, wear resistance, and corrosion resistance of the coatings were studied. The grain size of the high-speed laser cladding coating (HLC) was the smallest. The crystal structures of the plasma cladding coating (PC) and HLC were single face-centered cubic (FCC), while that of the deep laser cladding coating (DLC) was body-centered cubic (BCC). DLC had the best microhardness and wear resistance. The microhardness of PC, HLC, and DLC increased by 70%, 108%, and 109%, respectively, and the average friction coefficient decreased by 33%, 44%, and 51%, respectively, compared to Q235. HLC had the best corrosion resistance, with an annual corrosion rate of 0.66925 mm/a. The annual corrosion rate of PC and HLC was only 40% of Q235. The polarization curves of PC and HLC had obvious passivation regions with a width of up to 2 V. The corrosion types of PC were pitting corrosion and intergranular corrosion, that of HLC was general corrosion, and that of DLC was severe pitting corrosion.