摘要
采用恒应变速率法研究了Ti-15-3合金的超塑性变形行为以及变形过程中的显微组织演化。结果表明，n-15-3合金在变形温度为750-850℃，应变速率为3．2×10-5-2．2×10-3s-1的条件下获得了较好的超塑性，并且温度为800℃，应变速率为3．2×10-4s-1时，最大伸长率达到了565％。在最佳变形条件下，试样变形区发生了明显的动态再结晶，有利于原始B晶粒进一步细化，超塑性得到较大程度地提高。但随着变形温度的升高和应变速率的降低，高温下变形时间大幅延长，再结晶的B晶粒聚集长大，导致显微组织发生显著粗化，超塑性能下降。超塑性拉伸后，n-15-3合金断口上的空洞体积分数较高且空洞之间相互连接，变形温度对空洞尺寸影响显著，空位聚集和空洞连接是Ti-15-3合金超塑性断裂的主要机理。
Superplastic behaviour and microstructure evolution of Ti-15-3 alloy during superplastic deformation were studied by a constant strain rate method. The results indicate that the better superplasticity is obtained at temperatures which range from 750 to 850 ℃ and strain rates ranged from 3.2 x 10 -s to 2.2 -10 -3 s -1. The maximum tensile elongation attains 565% at the temperature of 800 ℃ and the strain rate of 3.2 x 10-4s-1. When the specimen is deformed at the optimum deformation conditions, dynamic recrystallization occurs in the deformed area obviously, which is favorable for further refining the coarsened 13 grains, so the superplasticity of Ti-15-3 alloy with large grain size has been greatly enhanced. With increasing temperature and decreasing strain rate, the recrystallized 13 grains grow together into larger grains due to increase of the deformation time at high temperature, leading to serious coarsening the microstructure, which decrease the supeplasticity. After superplastic deformation, the volume fraction of the cavities on the fracture of Ti-15-3 alloy is higher and the cavities link each other. The effect of the deformation temperature on the size of the cavities is obvious. The aggregation of vacancies and the linkage of cavities are the main mechanisms of suoerolastic fracture for Ti-15-3 alloy.
出处
《材料热处理学报》
EI
CAS
CSCD
北大核心
2013年第11期84-88,共5页
Transactions of Materials and Heat Treatment
基金
国家自然科学基金(51075196
51164029)
南昌航空大学轻合金加工科学与技术国防重点学科实验室基金(gf201101002)
江西省教育厅科技项目(GJJ13498)
关键词
TI-15-3合金
超塑性
再结晶
组织演化
Ti-15-3 alloy
superplasticity
recrystallization
microstructure evolution
