Comparative study on microstructures and properties of air-cooled and water-cooled Fe-based plasma arc cladding layers

In-situ V carbides reinforced Fe-based plasma arc cladding layers were prepared in the condition of air-cooled and water-cooled substrate, the microstructure, grain size and properties were comparatively studied. Results showed that microstructures of the two cladding layers were lath martensite. When the substrate was water-cooled, the residence times above 1495 °C decreased 46.3%, and the average cooling rates above 870°Cincreased 53.3%. The average grain size of the layers’ matrix and carbides was clearly refined from 3.12 to 1.39 μm and from 0.37 to 0.09 μm, respectively. Moreover, the depth of heat-affected zone reduced by 14.3%, and the dilution rate reduced by 16.90%. The comprehensive performances of the water-cooled cladding layer were obviously improved. The microhardness increased from 258 to 1040 HV0.2, the corrosion resistance increased 2.10 times and was about 13.75 times that of the low-carbon steel substrate.