组织性能的影响
(1. 西北工业大学 材料学院,西安 710072;2. 西北工业大学 凝固技术国家重点实验室,西安 710072;
3. 西安飞机工业(集团)有限责任公司,西安 710089)
摘 要: 在不同温度和时间下对TC18钛合金进行真空去应力退火处理,研究TC18钛合金真空去应力退火前后力学性能及残余应力的变化规律,观察去应力退火后的金相组织和拉伸断口形貌。结果表明:经真空去应力退火后,TC18钛合金的抗拉强度和屈服强度降低,冲击韧性、断裂韧性、伸长率和断面收缩率提高;残余应力消除效果显著;随着退火温度的升高,合金显微组织呈现规律性变化;当温度达到650 ℃以上时,α相明显减少,亚稳定β相显著增加,导致其强度下降,与力学性能测试结果相吻合;合金塑性提高,与断口形貌分析一致;最后,得到TC18钛合金的真空去应力退火制度为600~650 ℃和1~4 h。
关键字: TC18钛合金;残余应力;真空去应力退火;显微组织;力学性能
(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