The microstructure and erosive–corrosive wear performance of laser-clad Ni–Cr3C2 composite coating

The microstructure and erosive–corrosive wear (ECW) performance of laser-clad Ni–Cr3C2 composite coating with overlapping clad tracks on a 0.2% C martensitic stainless steel have been investigated by means of scanning electron microscopy (SEM), X-ray diffraction (XRD), energy dispersive X-ray analysis, microhardness testing and ECW testing. The average microhardness of the composite coating is increased with increasing amounts of added carbide in the considered range. The complete dissolution of Cr3C2 particles in the melted pool leads to carbon and chromium enrichment in the matrix, and hence causes the formation of M7C3 (M: Fe, Cr) in the solidifying structures. The clad layer consists of dense austenite (γ) dendrites surrounded by a γ-M7C3 eutectic. The ECW rate of the Ni–Cr3C2 coating decreased by about 50% as compared to the stainless steel substrate under the condition of acid slurry contained quartz sand. It is suggested that the improvement in ECW resistance is closely related to the formation of a more ductile austenite structure and the clad layer being strengthened due to the increase of coating hardness.