• CN:11-2187/TH
  • ISSN:0577-6686

机械工程学报 ›› 2022, Vol. 58 ›› Issue (16): 77-88.doi: 10.3901/JME.2022.16.077

• 特邀专栏: 高性能塑性成形制造(上) • 上一篇    下一篇

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新型三相TiAl合金高温塑性变形行为及流动软化研究

韩建超1,2, 姚昊明1,2, 贾燚1,2, 谢广明3, 王涛1,2   

  1. 1. 太原理工大学机械与运载工程学院 太原 030024;
    2. 太原理工大学先进金属复合材料成形技术与装备教育部工程研究中心 太原 030024;
    3. 东北大学轧制技术及连轧自动化国家重点实验室 沈阳 110819
  • 收稿日期:2021-12-13 修回日期:2022-06-09 出版日期:2022-08-20 发布日期:2022-11-03
  • 通讯作者: 王涛(通信作者),男,1985年出生,博士,教授,博士研究生导师。主要研究方向为金属塑性成形、轧制工艺与装备。E-mail:twang@tyut.edu.cn
  • 作者简介:韩建超,男,1989年出生,博士,副教授,硕士研究生导师。主要研究方向为金属塑性成形、金属复合板轧制变形。E-mail:hanjianchao@tyut.edu.cn
  • 基金资助:
    国家自然科学基金(51904205)、中央引导地方科技发展资金(YDZJSX2021A020,YDZX20191400002149)、轧制技术及连轧自动化国家重点实验室(东北大学)开放课题基金(2020RALKFKT014)、中国博士后科学基金(2018M641681)和山西省高等学校科技创新(2019L0216)资助项目

Studying on High Temperature Plastic Deformation Behavior and Flow Softening of Novel Multiphase TiAl Alloy

HAN Jianchao1,2, YAO Haoming1,2, JIA Yi1,2, XIE Guangming3, WANG Tao1,2   

  1. 1. College of Mechanical and Vehicle Engineering, Taiyuan University of Technology, Taiyuan 030024;
    2. Engineering Research Center of Advanced Metal Composites Forming Technology and Equipment, Ministry of Education, Taiyuan University of Technology, Taiyuan 030024;
    3. State Key Laboratory of Rolling and Automation, Northeastern University, Shenyang 110819
  • Received:2021-12-13 Revised:2022-06-09 Online:2022-08-20 Published:2022-11-03

摘要: 针对TiAl合金热塑性变形困难的问题,通过Gleeble-3800型热力模拟试验机,研究了新型三相Ti-40Al-6V-1Cr-0.3Ni合金在变形温度为1 100~1 225 ℃、应变速率为0.01~0.5 s-1、工程应变为70%条件下的热变形行为。采用Arrhenius双曲正弦函数模型推导出了该合金的本构方程,计算得出其热激活能和应力指数分别为464.74 kJ/mol和2.50,低于现有的变形TiAl合金。基于动态材料模型建立了合金在工程应变为70%时的热加工图。显微组织分析结果表明三相TiAl合金在高温和低应变速率下能进行充分的再结晶,表现出类似于高层错能合金的特征,同时由于V、Cr两种β相稳定元素的加入,拓宽了合金的热加工窗口。β相在高温变形过程中缓解加工硬化方面起到重要作用,其充分的再结晶和相变分解是缓解应力集中的主要方式,同时其作为高温润滑剂缓解晶界和相界处的应力,协调高温难变形α相的变形,改善了材料的热塑性变形能力。根据热加工图和显微组织特征,提出合适的热变形工艺参数,并成功地应用于TiAl合金的近等温无包套锻造。

关键词: 三相TiAl合金, 热塑性变形, 相变, 动态再结晶, 软化机制

Abstract: Focusing on the poor hot-deformability of TiAl alloy, the thermal deformation behavior of Ti-40Al-6V-1Cr-0.3Ni at deformation temperature of 1 100-1 225 ℃, strain rate of 0.01-0.5 s-1 and engineering strain of 70% is studied by Gleeble-3800 thermal simulation test machine. The constitutive equation of the alloy is deduced based on the Arrhenius hyperbolic sinusoidal function model. The activation energy and stress index are 464.74 kJ / mol and 2.50 respectively, lower than that of the present deforming TiAl alloy. Based on the dynamic material model, the hot working diagram of the alloy with the engineering strain of 70% is established. The microstructure analysis results show that the multiphase TiAl alloy could fully recrystallize at high temperature and low strain rate, showing a similar behavior to that of the alloy with high stacking fault energy. The addition of β phase stable elements widen the hot working window of the alloy. β Phase plays an important role in relieving work hardening during high-temperature deformation. The full recrystallization and phase transformation decomposition of β phase should be the main ways to alleviate stress concentration. At the same time, it acted as a high-temperature lubricant to alleviate the stress at grain boundary and phase boundary and coordinate the difficult deformation α phase at high temperature. As a result, the thermoplastic deformation ability of the material is improved. According to the hot working diagram and microstructure feature, the appropriate deformation process parameters are proposed and successfully applied to the nearly isothermal forging of TiAl alloy.

Key words: multiphase TiAl, thermoplastic deformation, phase transition, dynamic recrystallization, softening mechanism

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