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采用应变速率循环法对TA15钛合金进行三组高温超塑性拉伸试验,变形温度区间为850~950℃,应变速率循环区间为5×10-6~5×10-4s-1。分析拉伸试验数据后,计算出TA15钛合金动态再结晶激活能Q,结合金相组织分析得出其热变形过程中发生了动态再结晶的结论;并利用Arrhenius模型构建超塑性本构方程,应用origin数据处理软件进行数据分析,求得TA15钛合金高温条件下的超塑性本构方程。运用1stopt软件修正了该本构方程,使其精度达到99.3%。结果表明,TA15钛合金的流动应力对变形温度较为敏感,随着温度的升高,流变应力逐渐减小,软化机制愈发明显,且在900℃附近的超塑性较好,伸长率达到了846%。
Three sets of high temperature superplastic tensile tests were carried out on TA15 titanium alloy with strain rate cycling method. The deformation temperature range was 850-950 ℃ and the strain rate cycle range was 5 × 10-6 ~ 5 × 10-4s-1. After the tensile test data were analyzed, the dynamic recrystallization activation energy Q of TA15 titanium alloy was calculated, and the conclusion that dynamic recrystallization occurred during the thermal deformation process was obtained by metallographic analysis. The superplastic constitutive equation was established by Arrhenius model, The data of origin data processing software was used to analyze the superplastic constitutive equation of TA15 titanium alloy at high temperature. The constitutive equation was corrected with 1stopt software to achieve an accuracy of 99.3%. The results show that the flow stress of TA15 titanium alloy is more sensitive to the deformation temperature. With the increase of temperature, the flow stress decreases and the softening mechanism becomes more obvious. The superplasticity near 900 ℃ is good and the elongation reaches 846%.