The Effect of Solution Treatment Temperature on the Primary γ′ Phase and the Grain Structure in GH4251 Alloy

• Published in: Teshugang
• Main Authors: Tian Peiyu, Wang Hanxu, Li Xinyu
• Format: Article
• Language: Chinese
• Published: Editorial Office of Special Steel 2025-09-01
• Subjects: GH4215 Alloy; Primary γ′ Phase; Grain; Solution Treatment
• Online Access: http://www.specialsteeljournal.com/thesisDetails#10.20057/j.1003-8620.2025-00025
• ISSN: 1003-8620

Solution treatment temperature is a critical factor in regulating the precipitate and grain structure of superalloys. In this study， different solution treatment temperatures were applied to investigate the grain structure and the primary γ′ phase of a novel deformed nickel-based superalloy GH4251. The effects of solution treatment temperature on the microstructure were analyzed using multi-scale characterization analysis. The results show that both grain size and the volume fraction of primary γ′ phase decrease significantly with increasing solution treatment temperature. Particularly at the over-solid solution temperature， the primary γ′ phase is nearly entirely dissolved， causing the grain boundaries to lose their pinning force， which results in grain coarsening and a significant decrease in tensile strength and ductility. The increase in grain size is the primary cause of the reduced room-temperature tensile properties of the alloy. Statistical analysis of the equivalent particle radius （<italic>r</italic>） and volume fraction （<italic>f</italic>） of the primary γ′ phase in GH4251 was conducted， and data fitting was used to establish the relationship between these two parameters and the average grain size. The dissolution behavior of the primary γ′ phase in GH4251 alloy was analyzed from the perspective of atomic diffusion. It was observed that the γ′/γ interface of the primary γ′ phase exhibited enrichment of Cr and Co alongside depletion of Al， Ti， and Ta. Under the combined influence of solute element enrichment and the elastic stress field， the edges of the primary γ′ phase protruded， gradually detaching to form smaller γ′ particles. The elevated solid solution temperature accelerated this process， ultimately leading to the complete dissolution of the primary γ′ phase.