組織性能的影響
(1. 西北工業(yè)大學 材料學院，西安 710072；2. 西北工業(yè)大學 凝固技術(shù)國家重點實驗室，西安 710072；
3. 西安飛機工業(yè)(集團)有限責任公司，西安 710089)
摘 要: 在不同溫度和時間下對TC18鈦合金進行真空去應力退火處理，研究TC18鈦合金真空去應力退火前后力學性能及殘余應力的變化規(guī)律，觀察去應力退火后的金相組織和拉伸斷口形貌。結(jié)果表明：經(jīng)真空去應力退火后，TC18鈦合金的抗拉強度和屈服強度降低，沖擊韌性、斷裂韌性、伸長率和斷面收縮率提高；殘余應力消除效果顯著；隨著退火溫度的升高，合金顯微組織呈現(xiàn)規(guī)律性變化；當溫度達到650 ℃以上時，α相明顯減少，亞穩(wěn)定β相顯著增加，導致其強度下降，與力學性能測試結(jié)果相吻合；合金塑性提高，與斷口形貌分析一致；最后，得到TC18鈦合金的真空去應力退火制度為600~650 ℃和1~4 h。
關(guān)鍵字: TC18鈦合金；殘余應力；真空去應力退火；顯微組織；力學性能
（1. School of Materials Science and Engineering, Northwestern Polytechnical University, Xi’an 710072, China;
2. State Key Laboratory of Solidification Processing, Northwestern Polytechnical University, Xi’an 710072, China;
3. Xi’an Aircraft Industry (Group) Co. Ltd, Xi’an 710089, China）
Abstract:The different temperature and time parameters were adopted in the vacuum stress relieving annealing processes of TC18 titanium alloy. The evolution of mechanical properties and residual stress was researched, the microstructures and SEM images of fracture surfaces were also observed. The results show that, after the vacuum stress relieving annealing, the tensile and yield strengths of TC18 titanium alloy decrease, while the charpy toughness, fracture toughness, elongation and area reduction increase. The removing effect of residual stress is remarkable. Along with the increases of the temperature of stress relieving annealing, the microstructure of the alloy changes regularly. When the temperature exceeds 650 ℃, α-phase decreases obviously, and the metastable β-phase increases dramatically. Thus, the strength of the alloy decreases, which coincides with the result of mechanical properties. Meanwhile, the plasticity increases, which coincides with the fracture appearance. Finally, the vacuum stress relieving annealing schedule is obtained to be 600−650 ℃ and 1−4 h.
Key words: TC18 titanium alloy; residual stress; vacuum stress relieving annealing; microstructure; mechanical properties
