The Influence of Heat Treatment Process on the Microstructure and Properties of GH4080A Alloy

This study investigates the influence of six heat treatment processes on the microstructure and high-temperature mechanical properties of GH4080A alloy. The results indicate that, due to the incomplete dissolution of primary γʹ phase along grain boundaries, the variation in grain size is negligible as the solution temperature increases from 960 to 1070 ℃. Under the same solution temperature, specimens subjected to 850 ℃/24 h/AC followed by 700 ℃/16 h/AC aging exhibit significantly higher plasticity compared to those aged once at 700 ℃/16 h/AC. Furthermore, at solution temperatures below 1020 ℃, the secondary γʹ phases precipitated after aging at 850 ℃/24 h/AC are closer to a square morphology and, consequently, exhibit superior high-temperature mechanical properties when compared to those at 1070 ℃. Taking into consideration strength, toughness, and thermal processing costs, the optimum heat treatment process for GH4080A alloy is determined to be 1020 ℃/4 h/WQ + 850 ℃/24 h/AC + 700 ℃/16 h/AC. This is primarily attributed to the closer-to-square morphology and smaller size (20–40 nm) of the precipitated γʹ phases resulting from this heat treatment process.