Method for overlaying Co-Cr-W hard alloy on super duplex stainless steel substrate

The invention discloses a method for overlaying a Co-Cr-W hard alloy on a super duplex stainless steel substrate. By taking super duplex stainless steel as a substrate material, Co-Cr-W hard alloy is overlaid on the surface of the substrate material by virtue of argon tungsten-arc welding; the super duplex stainless steel consists of the following components in percentage by weight: 24-26% of Cr, 6-8% of Ni, 3-4% of Mo, 0.2-0.3% of N, 0.05-1% of Cu, 0.5-1% of W, less than or equal to 0.03% of C, less than or equal to 1.0% of Si, less than or equal to 1.0% of Mn, less than or equal to 0.03% of P, and less than or equal to 0.01% of S. According to the method, by researching material characteristics, optimizing process parameters and controlling quality in a welding process, the Co-Cr-W hard alloy is overlaid on the surface of the super duplex stainless steel substrate, so that test data which meets standard requirements of nuclear-power regulation RCC-M is obtained, and the corrosion problem, in a using process, of a nuclear-grade pump shaft sleeve substrate material is solved.