Development of Cobalt Free Alloy

It is very effective in reducing radiation damage to operators from exp 60 Co that a material containing no cobalt is used to replace Co containing Stellite alloys for atomic power stations. A new Ni-Cr-Mo-Nb alloy used as cast and build-up materials has been developed in view of limited applications of previously developed Ni-Cr-Al-Mo forging alloys. The alloy consists typically of Cr 26.2, Mo 12.8, Nb 11.0, Si 0.42 mass%, and Ni the balance. In high temperature and pressure water of simulative boiling water reactors, the alloy combination against surface nitrided materials displays excellent wear resistance compared to Co alloy combinations. Tests indicated that the Ni-Cr-Mo-Nb alloy, when used in built up welding, has a low wear amount and corrosion rate.