Study on Heat-treated microstructure of GH4169 superalloy deposited by UHFP-GTAW

Thin wall test specimen of GH4169 superalloy has been deposited by UHFP-GTAW, and two kinds of heat treatment methods were formulated. The specimens were divided into 3 groups:specimens without heat treatment, specimens with solution and aging heat treatment and homogenizing heat treatment, respectively, and their microstructures has been compared and analyzed after the electrochemical corrosion. The results showed that large size dentrite is the main microstructure of specimens without heat treatment, with a large amount of interdendritic Laves phase, which exits in a smaller size in the UHFP-GTAW specimens than the CP specimens. A mass of lamellar δ phase, γ″ phase, a certain amount of γ' phase and some Laves phases which remained on the dentrite can be observed on the γ matrix of the specimens treated by solution and aging heat treatment. The microstructure of specimens that are treated by homogenizing and aging heat treatment is mainly a large amount of graininess γ″ phase and γ' phase, and some small size Laves phases and MC type of carbide, while the δ phase has almost disappeared.