• CN:11-2187/TH
  • ISSN:0577-6686

机械工程学报 ›› 2022, Vol. 58 ›› Issue (6): 42-51.doi: 10.3901/JME.2022.06.042

• 材料科学与工程 • 上一篇    下一篇

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基于热激活变形理论的铝合金弹塑性应力松驰机理与建模

李勇1,2, 石朱生3, 吕凤工4, 荣琦3, 李东升1, 林建国3   

  1. 1. 北京航空航天大学机械工程及自动化学院 北京 100191;
    2. 深圳北航新兴产业技术研究院 深圳 518057;
    3. 帝国理工学院机械工程学院 伦敦 SW7 2AZ 英国;
    4. 中国航空制造技术研究院 北京 100024
  • 收稿日期:2021-06-26 修回日期:2021-11-10 出版日期:2022-03-20 发布日期:2022-05-19
  • 通讯作者: 李勇,男,1989年出生,博士,教授。主要研究方向为轻量化材料加工成形工艺研发、多尺度材料本构建模等。E-mail:liyong19@buaa.edu.cn
  • 基金资助:
    国家自然科学基金(52005020)和广东省基础与应用基础研究基金(2019A1515110851)资助项目。

Mechanism and Modelling Studies of Elastic-plastic Stress Relaxation of Aluminium Alloys Based on Thermally Activated Plastic Theories

LI Yong1,2, SHI Zhusheng3, Lü Fenggong4, RONG Qi3, LI Dongsheng1, LIN Jianguo3   

  1. 1. School of Mechanical Engineering and Automation, Beihang University, Beijing 100191;
    2. Shenzhen Institute of Beihang University, Shenzhen 518057;
    3. Department of Mechanical Engineering, Imperial College London, London SW7 2AZ, UK;
    4. AVIC Manufacturing Technology Institute, Beijing 100024
  • Received:2021-06-26 Revised:2021-11-10 Online:2022-03-20 Published:2022-05-19

摘要: 针对铝合金在弹、塑性阶段应力松驰现象存在的机理不一致、预测模型不足问题,提出一种利用热激活塑性变形理论进行弹性和塑性区域铝合金应力松弛时效(Stress relaxation ageing,SRA)过程中变形机理表征和建模的方法。基于该方法,对7B04和6082铝合金SRA试验结果开展分析,获得的表观激活体积表明,二者在弹性和塑性区域的应力松驰特性均由位错-第二相相互作用机制主导。弹性区域中应力松弛行为主要受有效应力分量影响,而塑性区域中更显著的应力松弛现象则归结于有效应力增加和表观激活能降低的综合作用。基于理论分析与量化结果,提出了一种考虑表观能量变化的材料本构模型,实现对于铝合金在弹塑性变形区域内各类应力水平下的不同应力松弛行为的高效预测,为其潜在蠕变时效成形工艺应用奠定精确模型基础。提出的方法克服了常规蠕变应力指数分析方法用于弹塑性SRA特性分析时的局限性,并提供了丰富的量化信息(包括应力分量,表观激活体积和能量等),支撑铝合金SRA变形机制和特性的表征与精确模拟。

关键词: 铝合金, 应力松驰成形, 内应力, 有效应力, 激活能, 本构模型

Abstract: Aiming at the inconsistent of mechanisms and insufficient prediction models for stress relaxation of aluiminium alloys in elastic and plastic regions, a method that utilises thermally activated plastic deformation theories for mechanism characterisation and modelling during stress relaxation ageing (SRA) process in both elastic and plastic regions is proposed. The apparent activation volumes obtained from the theories for AA7B04 and AA6082 alloys indicate a dislocation-obstacles interaction mechanism for stress relation in both elastic and plastic regions. The stress relaxation behaviour in elastic region is found to be mainly affected by the effective stress, while the more significant stress relaxation in plastic region has been attributed to the combined effect of increasing effective stresses and decreasing apparent activation energies, which have been quantified by the theories in this study. Based on these theoretical analysis results, a simple constitutive model considering the changing apparent energies has been proposed, providing an effective way to successfully predict the different stress relaxation behaviour of aluminium alloys under various stress levels in the elastic-plastic deformation range for potential CAF process applications. The proposed method overcomes limitations of the conventional creep stress exponent analysis method for SRA behaviour analysis, and provides abundant information (i.e. stress components, apparent activation volumes and energies) to support the characterization of deformation mechanisms in SRA and enable accurate prediction of different SRA behaviour in elastic and plastic regions.

Key words: aluminium alloys, stress relaxation, internal stress, effective stress, activation energy, constitutive modelling

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