Effect of Silicon on Microstructure and Wear Property of As-Cast High-Vanadium Wear-Resistant Alloys

Silicon significantly affects the microstructure and properties of wear-resistant alloys. To investigate the effect of silicon content on the microstructure and properties of high-vanadium wear-resistant alloys (HVWA), three alloys with different silicon content (HVWA-0.66Si, HVWA-2.14Si and HVWA-5.17Si) were formulated and synthesized. And the solidification structure and wear behavior of HVWAs were researched. The increased content of silicon enhances the precipitation temperature of VC and therefore promotes the formation of more pellet/agglomerate primary VC in solidification and decreases the content of strip eutectic VC. The as-cast structure of HVWAs comprises of pearlite, with numerous submicron carbides dispersed on the pearlite matrix. The increased content of silicon increases the lamellar spacing of pearlite and the particle size of submicron carbides. The lamellar spacing of pearlite in HVWA-0.66Si, HVWA-2.14Si and HVWA-5.17Si measures 50–300 nm, 200–600 nm and 300–1800 nm, correspondingly, while the size of the submicron carbides is 0.3–0.9 μm, 0.5–1.3 μm and 0.3–1.9 μm, accordingly. The impact toughness of the alloy reduces as the silicon content increases. The HVWA-5.17Si matrix has a hardness of 49.3 HRC and boasts exceptional wear resistance. Taking HVWA-0.66Si as a reference, the relative wear resistance ε of HVWA-5.17Si has the highest wear resistance, with ε reaching 1.75. The strong wear resistance of HVWA-5.17Si stems mainly from the solid solution of silicon in the matrix that heightens its hardness. This feature works in tandem with the high-hardness primary VC and an abundance of finely formed secondary vanadium carbides that precipitate in the as-cast alloy.