Crack‐Free Welding of a Co‐Base Superalloy with High γ' Precipitate Fraction

Laser cladding of superalloys provides an attractive and cost‐efficient technique for near‐net shape manufacturing, remanufacturing, or individualized repair of components. While the weldability of γ' hardened Ni‐base superalloys is limited, Co‐base superalloys should have a lower susceptibility for cracking during welding due to a lower γ' solvus temperature and less segregation than Ni‐base superalloys. The weldability of the Co‐base superalloy CoWAlloy2Mod and the resulting mechanical properties at 950 °C are investigated. In the as‐welded condition of CoWAlloy2Mod, a fine dendritic microstructure without forming cracks and limited porosity is found. After a three‐step heat treatment, recrystallized, equiaxed grains and a high γ' volume fraction are obtained leading to a very good strength. CoWAlloy2Mod shows a significantly higher strength and creep strength than the conventional weld filler Co‐alloy PWA795.