Effects of vanadium additive on structure property and tribological performance of high chromium cast iron hardfacing metal

Hard and wear-resistance layer of high chromium cast iron (HCCI) with vanadium additive was prepared by surfacing technology. Using DSC the phase transition temperature curve of surfacing alloy layer was examined. The content of carbide in hardfacing layer was further determined through microstructure analysis. Meanwhile, iron–carbon equilibrium phase diagram of hardfacing layer was calculated. In addition, the wear-resistance of hardfacing layer was carried out. The results show that the carbide precipitated from hardfacing layer is the type of M7C3. Primary, eutectic and secondary carbides are approximately hexagonal structure, long rods and fine spherical, respectively. However, the secondary carbide VC is precipitated from the hardfacing layer when vanadium additive was added into flux cored wire. As the content of vanadium additive increases in the flux-cored wire, the size of primary carbide significantly reduces and the amount of eutectic and secondary carbides gradually increase. Therefore, the improvement of wear-resistance of surfacing layer was mainly due to the vanadium additive in flux-cored wire.

Research highlights
► The primary, eutectic and secondary carbide are hexagonal, rod and fine spherical, respectively.
► The microstructure of hardfacing metal is refined with the increase of vanadium (V) additive.
► The amount of primary carbide is reduced and the eutectic carbide increased with the increase of V.
► The wear-resistance of hardfacing metal is increased with the increase of vanadium additive.