Keyhole TIG Welding of New Co-Lean Nickel-Based Superalloy G27

Abstract

The influence of keyhole TIG (K-TIG) weldingWelding parameters on the weld geometryWeld geometry and defects of a new Co-lean nickel-based superalloyNickel-based superalloys G27 was studied, and the microstructuresMicrostructures of the heat-affected zone (HAZ) and fusion zone (FZ) of the K-TIG-welded Alloy G27 were characterized. No cracks are found in the FZ and HAZ. Minimum weld width and face underfill statistically were significantly influenced by travel speed and interaction current*travel speed. Root excess weld metal was only significantly influenced by travel speed. Face excess weld metal was significantly influenced by all the factors, including their interaction. On the other hand, all the factors, including their interaction, did not significantly influence the average pore diameter. In the FZ microstructureMicrostructures, interdendritic microconstituents are identified as (Nb, Ti)C particles and γ/Laves eutectic constituents. In addition, a plate-like phase is observed surrounding the Laves phaseLaves phases, and γʹ precipitates are found to be inhomogeneously precipitated in the FZ. In the partially melted zone (PMZ), (Nb, Ti)C, Laves phaseLaves phases, γʹ precipitates, and plate-like particles are found in the liquated and resolidified regions, suggesting the solidification behavior in PMZ is likely to follow a similar pattern to the one observed in FZ.