固溶和时效温度对7715D钛合金组织和性能的影响

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

研究了固溶和时效温度对7715D高温钛合金轧棒室温和600℃高温拉伸性能的影响。结果表明,低温固溶材料室温强度高,但高温强度低;低于600℃时效时材料的室温屈服强度和塑性变化不大;高于600℃时效,室温强度略有上升,高温强度降低。组织和拉伸断口分析表明,室温强度与β转变组织大小相关,高温强度受初生α相和β转变组织的相对强度影响更大。建议7715D钛合金在高的固溶温度和适当的时效温度进行热处理,推荐980℃/2 h+600℃/2 h。

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. Results showed 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.