Microstructure evolution during hot deformation and dynamic transformation of Ti-5Al-3.3Sn-3.7Zr-0.6Ta-0.5W alloy in α + β two-phase region
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摘要: 采用热压缩试验和微观组织表征试验相结合的方法，探究一种新型近α型钛合金在不同变形条件下的流变行为和微观组织演变。研究发现，真实应力−应变曲线显示出峰值后应力整体下降并趋于稳定的特点，并且在高应变速率下，峰值应力较高且迅速下降。这是硬取向的α相向软取向的β相的转变导致了流变应力的快速下降，以及动态再结晶细化晶粒和动态回复对于亚晶组织中位错的排布。基于这些发现建立了动态再结晶体积分数模型。Abstract: The rheological behavior and microstructure evolution of the new near-α titanium alloy under different deformation conditions were investigated by thermal compression tests and microstructure characterization experiments. The results show that the real stress-strain curve displays characteristics of stress decrease and tendency to stabilize after the peak. At high strain rates, the peak stress is high and decreases rapidly. The transformation of the hard-oriented α phase to the soft-oriented β phase leads to a rapid decrease in the flow stress, with dynamic recrystallization (DRX) refining grains and dynamic recovery (DRV) rearranging dislocations within subgrains. Based on these findings, a dynamic recrystallization volume fraction model was established.
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图 3 在不同变形温度下Ti-5Al-3.3Sn-3.7Zr-0.6Ta-0.5W合金的真应力−应变曲线
Figure 3. True stress-strain curve of Ti-5Al-3.3Sn-3.7Zr-0.6Ta-0.5W alloy at various deformation temperatures
图 4 Ti-5Al-3.3Sn-3.7Zr-0.6Ta-0.5W合金的峰值应力与变形条件之间的关系
Figure 4. Relationship between peak stress and deformation conditions for Ti-5Al-3.3Sn-3.7Zr-0.6Ta-0.5W alloy
图 10 变形温度为940 ℃、应变速率为1 s−1时的EBSD
Figure 10. EBSD at deformation temperature of 940 ℃ and strain rate of 1 s−1
图 11 沿CD方向加载时基面<a>和柱面<a>滑移的施密特因子分布
Figure 11. Distribution of Schmid factors for basal <a> slip and prismatic <a> slip along CD direction
图 12 应变硬化速率与流变应力之间关系示意图
Figure 12. Schematic diagram of relationship between strain hardening rate and flow stress
图 13 在不同热变形条件下Ti-5Al-3.3Sn-3.7Zr-0.6Ta-0.5W合金的
$ \theta $ -$ \sigma $ 曲线Figure 13.
$ \theta $ -$ \sigma $ curve of Ti-5Al-3.3Sn-3.7Zr-0.6Ta-0.5W alloy under different hot deformation conditions
图 14 确定Ti-5Al-3.3Sn-3.7Zr-0.6Ta-0.5W合金DRX动力学模型参数K和B
Figure 14. Determining parameters K and B of DRX kinetic model for Ti-5Al-3.3Sn-3.7Zr-0.6Ta-0.5W alloy
表 1 Ti-5Al-3.3Sn-3.7Zr-0.6Ta-0.5W合金化学成分
Table 1. Main chemical composition of Ti-5Al-3.3Sn-3.7Zr-0.6Ta-0.5W alloy
元素 Al Zr Sn Ta W Ti 质量分数/% 5.0 3.7 3.3 0.6 0.5 Bal. 
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