Effects of Nb on microstructure and wear resistance of Fe–Cr–C–B surfacing alloy

The influence of Nb on the microstructure and wear resistance of the surfacing layer was investigated by using the Fe-based flux-cored wire in the Fe–Cr–C–B system. The microstructure, microhardness and wear resistance properties of the samples were investigated by X-ray diffraction, scanning electron microscopy, microhardness testing and abrasive wear testing, respectively. The results indicate that microstructures of the alloy are composed of martensite, retained austenite, M₂₃(C,B)₆ and NbC. Boride M₂₃(C,B)₆ is distributed along the grain boundaries, while NbC in shape-regular quadrilateral is distributed in martensite. The microhardness is distributed from the substrate to the surfacing layer gradiently. NbC significantly improved the wear resistance of surfacing layer.