Microstructural Analysis of Fusion Zone in Gas Tungsten Arc-Welded Newly Developed Co-Based Superalloy

The fusion zone (FZ) microstructure of a newly developed gas tungsten arc-welded cobalt-based superalloy called CoWAlloy1 is characterized. Elemental microsegregation leads to the formation of interdendritic micro-constituents, which are confirmed to include MC-type carbides and γ - γ ' eutectics, as well as inhomogeneous precipitation of γ ' within the FZ. The presence of the terminal solidification reaction products and inhomogeneous distribution of γ ' in the FZ require appropriate consideration during the development of optimal post-weld heat treatment.