Effects of Solution Temperature on the Microstructural Evolution and Mechanical Properties of the GH4706 Alloy
摘要
The microstructural evolution and mechanical properties of the GH4706 alloy were investigated at the solution temperatures of 940°C (HT940), 980°C (HT980), and 1010°C (HT1010). The results indicate that both the average grain size and the fraction of twin boundaries increase as the solution temperature increases, whereas the HT940 sample exhibited serrated grain boundaries and numerous low-angle grain boundaries. The size of the η phase decreases as the solution temperature increases. The catenulate γ′-γ″ eutectoid microstructure with a large size and the η phase partially precipitate in the grains of the HT940 sample under high distortion energy. The room-temperature yield strength of the HT940 sample is improved owing to the large size of the γ′-γ″ eutectoid microstructure, the high dislocation density, and the fine grains hindering the dislocation motion. The rupture life is the longest in HT940, followed by HT980 and HT1010, which is attributed to the large sizes of the γ′-γ″ eutectoid microstructure and η phase, serrated grain boundaries, high dislocation density, and low fraction of twin boundaries, which hinder crack propagation. The η phase in the grain cannot deform cooperatively with the γ matrix, resulting in transgranular fracture of the ruptured HT940 sample.