(1. 中南大学 机电工程学院，长沙，410083；
2. 中南大学 材料科学与工程学院，长沙，410083；
3. 中南大学 粉末冶金国家重点实验室，长沙，410083；
4. 中国石油天然气集团公司管材研究所，西安，710065；
5. 陕西省天然气股份有限公司 安全与环境监察部，西安，710016)
摘 要: 本文研究了固溶时效及固溶预拉伸时效对挤压态Ti-5.5Al-2Zr-1Mo-2.5V钛合金管材微观组织演变、相组成及室温力学性能的影响。结果表明：高温固溶过程中，片状α相内缠结位错通过运动及反应演化成位错阵列，进而形成亚晶界，三角亚晶界形成热沟槽并扩展造成片状α相断裂。同时，淬火以及淬火后预拉伸引入的大量缺陷成为后续时效过程次生α相析出的形核位点，进而诱导次生α相数量增加、尺寸变小。淬火试样在450 °C时效2 h后室温屈服强度提高30%，达1064 MPa，同时还具有10.5%的均匀伸长率；而2.5%预拉伸后时效样品屈服强度提升53%，达1260 MPa，但伸长率下降至4.8%。
关键字: 近α钛合金管材；固溶时效；预拉伸；微观组织；强韧性
（1. School of mechanical and electrical engineering, Central South University, Changsha 410083, China;
2. School of materials science and engineering, Central South University, Changsha 410083, China;
3. State Key Laboratory of powder metallurgy, Central South University, Changsha 410083, China;
4. Tubular Goods Research Institute of CNPC, Xi''an 710065, China;
5. Ministry of Safety and Environment Supervision, Shaanxi Provincial Natural Gas Co., Ltd., Xi''an 710016, China）
Abstract:The influence of solution aging and pre-stretching aging on microstructure evolution and tensile properties of the extruded Ti-5.5Al-2Zr-1Mo-2.5V titanium alloy pipe was investigated. The results indicate that the tangled dislocations within the lamellar α phase evolved into dislocation arrays through movement and reaction, then formed into the subgrain boundary, and the thermal groove developed at the triangle boundary of the subgrain gave rise to the lamellar α phase breaking during the solid solution treatment. Meanwhile, a large quantity of defects introduced by quenching and pre-stretching became nucleation sites of the precipitation of secondary α phase during subsequent aging, which induced the increase of the volume fraction and lower size of secondary α phase. After aging at 450 °C / 2 h, the yield strength of the quenching sample increased by 29% to 1064 MPa, and the elongation remained at 10.5%; while 2.5% pre-stretching brought about 53% increment of the yield strength, but the elongation decreased to 4.8%.
Key words: near alpha titanium alloy；solution and aging；pre-stretching；microstructure；strength and ductility
