(1. 中南大學(xué)機(jī)電工程學(xué)院，長(zhǎng)沙
410083；
2. 中南大學(xué)材料科學(xué)與工程學(xué)院，長(zhǎng)沙 410083；
3. 中南大學(xué)粉末冶金國(guó)家重點(diǎn)實(shí)驗(yàn)室，長(zhǎng)沙 410083；
4. 中國(guó)石油天然氣集團(tuán)公司管材研究所，西安 710065；
5. 陜西省天然氣股份有限公司安全與環(huán)境監(jiān)察部，西安 710016)
摘 要: 本文研究了固溶時(shí)效及固溶預(yù)拉伸時(shí)效對(duì)擠壓態(tài)Ti-5.5Al-2Zr-1Mo-2.5V鈦合金管材微觀組織演變、相組成及室溫力學(xué)性能的影響。結(jié)果表明：高溫固溶過(guò)程中，片狀α相內(nèi)纏結(jié)位錯(cuò)通過(guò)運(yùn)動(dòng)及反應(yīng)演化成位錯(cuò)陣列，進(jìn)而形成亞晶界，三角亞晶界形成熱溝槽并擴(kuò)展造成片狀α相斷裂。同時(shí)，淬火以及淬火后預(yù)拉伸引入的大量缺陷成為后續(xù)時(shí)效過(guò)程次生α相析出的形核位點(diǎn)，進(jìn)而誘導(dǎo)次生α相數(shù)量增加、尺寸變小。淬火試樣在450 ℃時(shí)效2 h后室溫屈服強(qiáng)度提高30%，達(dá)到1064 MPa，同時(shí)還具有10.5%的斷裂總伸長(zhǎng)率；而2.5%預(yù)拉伸時(shí)效樣品屈服強(qiáng)度提升53%，達(dá)到1260 MPa，但伸長(zhǎng)率下降至4.8%。
關(guān)鍵字: 近α鈦合金管材；固溶時(shí)效；預(yù)拉伸；微觀組織；強(qiáng)韌性
（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. Department 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 evolves into dislocation arrays through movement and reaction, then forms into the subgrain boundary, and the thermal groove develops 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 become nucleation sites of the precipitation of secondary α phase during subsequent aging, which induces the increasing number and lower size of secondary α phase. After aging at 450 ℃ for 2 h, the yield strength of the quenching sample increases by 29% to 1064 MPa, and the elongation remains at 10.5%; while 2.5% pre-stretching brings about 53% increment of the yield strength, but the elongation decreases to 4.8%.
Key words: near alpha titanium alloy; solution and aging; pre-stretching; microstructure; strength and ductility
