Microstructure, Wear Resistance and Corrosion Resistance of FeNiCrMo, FeNiCrMo/WC and FeNiCrMo/WC-17Co Coatings Prepared by Laser Cladding: A Comparative Study

FeNiCrMo austenitic stainless steel has good corrosion resistance but a low surface hardness, which limits its wear resistance under high load. FeNiCrMo, FeNiCrMo with 10 wt.% tungsten carbide (WC) (45–106 μm) and FeNiCrMo with 10 wt.% WC-17Co (15–45 μm) were deposited by laser cladding at 1200 W and 480 mm/min, and their phase composition, microstructure, microhardness, wear behaviour and corrosion resistance were compared. Both particle additions promoted a columnar-to-equiaxed transition and the formation of W2C. The coarse WC particles dissolved only partially and raised the hardness little, from 473 to 475 HV0.2, while the finer WC-17Co particles dissolved more completely and raised it to 550–600 HV0.2. On the worn surfaces, the ploughing grooves of the unreinforced coating were still present but shallower and narrower, indicating that abrasion was reduced in severity rather than replaced. The particles nevertheless impaired the corrosion resistance, most strongly for WC-17Co. FeNiCrMo/WC gave the best overall result. Its specific wear rate was the lowest of the three coatings, 0.73 × 10−6 mm3·N−1·m−1 at 90 N and roughly an order of magnitude below the unreinforced coating, and its mass loss was the smallest at every load, while its corrosion resistance fell far less than that of FeNiCrMo/WC-17Co, with an Ecorr of −0.393 V against −0.738 V. The coarse, only partly dissolved WC particles provide the most favourable combination of wear and corrosion resistance and are recommended for FeNiCrMo components operating under high load in only mildly aggressive conditions.