再次热处理对TC4-DT钛合金板材组织及性能的影响

Effects of Re-heat Treatment on Microstructure and Mechanical Property of TC4-DT Titanium Alloy Plates

经β退火后的TC4-DT钛合金板材,其强度未达到AMS 4905标准要求。为此,在β单相区和α+β两相区分别又进行了固溶(冷却方式分别为空冷和水冷)加时效处理。观察了经不同工艺热处理后板材的显微组织,并对其室温拉伸性能、断裂韧性进行了测试分析。结果表明,再次热处理后板材组织未发生明显改变。与空冷态相比,水冷后的次生α更细小。与原始β退火相比,水冷后板材的拉伸强度、屈服强度增加约70 MPa,同时断裂韧性略有减小,延伸率略降至8.5%。经再次热处理后,板材的强度和断裂韧性均达到标准要求。

The tensile properties of β annealed TC4-DT titanium alloy plates could not meet the standard requirements, so solution and aging treatment in single β phase region and α ＋β phase region were performed. The mierostructure, room-temperature tensile properties and fracture charaeleristies under different treated conditions were investigated. The results show that the mierostructure of the samples after re-heat treatment has no remarkable changes. Compared to that of the samples by the air cooling, the refiner secondary α is attained hy water cooling. The tensile strength and yieht strength of the samples hy water quenching increase by about 70 MPa compared with the origina β annealed samples, whereas the fracture toughness slightly decreases, and the elongation is 8.5%. Thus the good performance matching is achieved.