退火处理对Ti-2Al-2.5Zr钛合金管再结晶行为的影响

    Effect of Annealing Treatment on Recrystallization Behavior of Ti-2Al-2.5Zr Titanium Alloy Tubes

    • 摘要: 系统研究了冷轧态Ti-2Al-2.5Zr合金管材在650、700和750 ℃等温再结晶退火过程中的微观组织演变和力学性能变化。采用电子背散射衍射(EBSD)、光学显微镜及拉伸测试等手段,分析了不同退火工艺下合金的微观组织演变规律及形变储能释放特征。研究表明:Ti-2Al-2.5Zr钛合金再结晶退火由温度与保温时间共同调控,其中退火温度起主导作用,700 ℃保温90 min为最佳退火工艺;合金再结晶过程具有明显的阶段性,退火初期约80%基体可快速完成再结晶;第二阶段再结晶行为变得迟缓,(0,35°,30°)取向的晶粒具有明显的再结晶“抵抗”效应;再结晶退火后合金基本保留冷轧态原有主织构,晶粒取向呈现由<\!\!10\bar10\!\!>\!\!\|\mathrmAD向<\!\!1\,1\bar20\!\!>\!\!\|\mathrmAD转变的趋势。研究结果可为Ti-2Al-2.5Zr钛合金管材退火处理工艺制度优化提供理论依据。

       

      Abstract: The microstructural evolution and mechanical properties of cold-rolled Ti-2Al-2.5Zr alloy tubes during isothermal recrystallization annealing at 650 ℃, 700 ℃ and 750 ℃ were investigated. Electron backscatter diffraction (EBSD), optical microscopy and tensile tests were employed to analyze the microstructural evolution and strain energy release behavior of the alloy under different annealing process. The results reveal that the recrystallization behavior of Ti-2Al-2.5Zr titanium alloy is jointly regulated by annealing temperature and holding time, with temperature playing a dominant role. The optimal annealing parameter is determined to be holding at 700 ℃ for 90 min. The recrystallization process presents distinct staged characteristics. In the first stage of annealing, 80% of the matrix undergoes rapid recrystallization, while the recrystallization proceeds very slowly in the second stage. The grains with the orientation of (0, 35°, 30°) exhibit resistance to recrystallization. The main texture components of the cold-rolled state are largely retained after recrystallization annealing, and the grain orientation tends to transform from <\!\!10\bar10\!\!>\!\!\|\mathrmAD to <\!\!1\,1\bar20\!\!>\!\!\|\mathrmAD during recrystallization. The above findings provide a theoretical basis for the optimization of annealing process schedules for Ti-2Al-2.5Zr titanium alloy tubes.

       

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