Influence of Solution and Aging Temperature on Microstructures and Mechanical Properties of 7715D Titanium Alloy

The influences of solution and aging temperatures on tensile properties of a high-temperature Ti alloy (7715 D) rolling bar at room temperature (RT) and 600 ℃ were studied.Resultsshowed that lower solution temperature tends to lead high RT strength, but low high-temperature strength; when the ageing temperature is lower than 600 ℃, the RT strength and ductility vary slightly; when the aging temperature is higher than 600 ℃, the RT strength increases slightly, but the 600 ℃ high-temperature strength decreases. The microstructure and fractography analysis show that the RT strength is related to the size of β transformed microstructure, and the high-temperature strength is more influenced by the relative strength of the primary α and β transformed microstructure. As 7715 D is more concerned with its high-temperature strength, it is recommended that heat treatment is performed at high solid solution temperature and medium aging temperature, that's, 980 ℃/2 h+600 ℃/2 h.