The vacuum melting alloy screw is made of steel core and nicrbfe (SI) or nicrbfe (SI) + WC by vacuum powder metallurgy in special steel mould. The core structure of the screw is pearlite or martensite, and the surface is martensite or martensite plus tungsten carbide. The screw has excellent strength, toughness, surface hardness and corrosion resistance. It is widely used in injection molding of PC, PE, PA, PS, PMMA, ABS, PVC, PSU, POM, plastic wood, aluminum plastic, transparent plastic, etc.