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Ti-62A合金热变形过程中的流变应力特性及组织演变
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西安建筑科技大学冶金工程学院

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国家自然科学基金资助(项目号51474170)


Flow stress characteristics and microstructure evolution during hot compression of Ti-62A alloy
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    摘要:

    通过 Gleeble-3800 热模拟试验机的热压缩实验,研究了 Ti-62A 合金在 800、850、900 和 950℃,应变速率为 0.001、0.01、0.1 和 1s-1 下的热变形行为和动态再结晶(DRX)规律。结果表明:Ti-62A 合金的流变应力受应变速率和变形温度的影响显著;流变应力随着变形温度的升高和应变速率的降低而降低;在 900~950℃、应变速率 0.01~1s-1 条件下,Ti-62A 合金的热变形应力-应变曲线属于动态回复型;该合金的热变形机制主要由位错运动控制,其动态软化机制包括晶界滑动和位错对消、攀移机制;Ti-62A 合金在热变形过程中,动态再结晶更有可能发生在较高的温度和较低的应变速率下,即 950℃ 和 0.001s-1;基于经典位错密度理论和 DRX 动力学理论,建立了加工硬化—动态回复和 DRX 软化效应的两阶段本构模型。DEFORM-3D 软件的仿真模拟结果证实,基于 DRX 软化效应的本构模型对 Ti-62A 合金在动态再结晶阶段的热变形行为的预测具有较高的准确性,能够为实际生产工艺的制定提供技术参考。

    Abstract:

    The hot deformation behavior and dynamic recrystallization (DRX) of Ti-62A alloy at 800, 850, 900 and 950 ℃and strain rates of 0.001, 0.01, 0.1 and 1 s-1 were studied by hot compression experiments on Gleeble-3800 thermal simulator. The results show that the flow stress of Ti-62A alloy is significantly affected by strain rate and deformation temperature. The flow stress decreases with the increase of temperature and the decrease of strain rate. At 900~950 ℃ and strain rate of 0.01~1 s-1, the thermal deformation stress-strain curve of Ti-62A alloy belongs to dynamic recovery type, and the thermal deformation mechanism of the alloy is mainly controlled by dislocation movement, and its dynamic softening mechanism includes grain boundary sliding, dislocation cancellation and climbing mechanism; During hot deformation of Ti-62A alloy, dynamic recrystallization are more likely to occur at higher temperatures and lower strain rates, i.e. 950 ℃and 0.001 s-1. Based on the classical dislocation density theory and DRX dynamics theory, a two-stage constitutive model of work hardening — dynamic recovery and DRX softening effect is established. The simulation results of DEFORM-3D software confirm that the constitutive model based on DRX softening effect has high accuracy in predicting the thermal deformation behavior of Ti-62A alloy in the dynamic recrystallization stage, which can provide technical reference for the actual production process.

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丁凯伦,杨西荣,刘晓燕,杨雨欣. Ti-62A合金热变形过程中的流变应力特性及组织演变[J].稀有金属材料与工程,2020,49(9):3107~3114.[Ding Kailun, Yang Xirong, Liu Xiaoyan, Yang Yuxin. Flow stress characteristics and microstructure evolution during hot compression of Ti-62A alloy[J]. Rare Metal Materials and Engineering,2020,49(9):3107~3114.]
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  • 收稿日期:2019-09-25
  • 最后修改日期:2019-12-26
  • 录用日期:2020-01-03
  • 在线发布日期: 2020-10-15
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