金属热处理 ›› 2020, Vol. 45 ›› Issue (10): 44-47.DOI: 10.13251/j.issn.0254-6051.2020.10.009

• 工艺研究 • 上一篇    下一篇

预应变及时效处理对7A55铝合金残余应力及组织性能的影响

王淑慧1, 杨春苗1, 宋伟2, 盛光英1   

  1. 1.烟台南山学院 工学院, 山东 烟台 265713;
    2.山东南山铝业股份有限公司 国家铝合金压力加工工程技术研究中心, 山东 烟台 265700
  • 收稿日期:2020-03-20 出版日期:2020-10-25 发布日期:2020-12-29
  • 作者简介:王淑慧(1981—),女,讲师,硕士,主要研究方向为金属材料热处理过程组织性能优化,E-mail: wangshuhui132@163.com
  • 基金资助:
    山东省自然科学基金(ZR2016EMQ11)

Effect of pre-strain and aging treatment on residual stress, microstructure and properties of 7A55 aluminum alloy

Wang Shuhui1, Yang Chunmiao1, Song Wei2, Sheng Guangying1   

  1. 1. College of Engineering, Yantai Nanshan University, Yantai Shandong 265713, China;
    2. National Engineering Research Center for Plastic Working of Aluminum Alloys, Shandong Nanshan Aluminum Co., Ltd., Yantai Shandong 265700, China
  • Received:2020-03-20 Online:2020-10-25 Published:2020-12-29

摘要: 研究了预应变和时效处理对7A55铝合金残余应力和组织演变的影响。利用透射电镜和EBSD观察了微观组织,XRD测试了残余应力,显微硬度计测试了维氏硬度。试验结果表明:固溶后的试样,表面为压应力,沿轧制方向为-75 MPa,横向-115 MPa。经不同的预应变后,表面残余应力逐渐降低,施加2%的预应变后基本消除。180 ℃的时效温度下,残余应力的消减速度显著高于100 ℃和140 ℃下。随预应变量的增大,显微硬度逐渐增大,经3%的预应变后增大为92 HV0.5,提高了27.8%。显微硬度随时效时间的增加先增高后降低,峰值出现在15 h,100、140和180 ℃下时效时分别达到135、143和162 HV0.5。100 ℃×15 h的峰值硬度下晶内主要析出亚稳η′相,与基体呈共格关系;140 ℃时晶内析出相尺寸变大,出现圆片状η′相,与基体呈半共格关系;180 ℃时出现了短棒状η′相,尺寸达到5~20 nm,位相差小于10°的小角度晶界占了80%以上。

关键词: 7A55铝合金, 残余应力, 预应变, 时效

Abstract: Effect of pre-strain and aging treatment on the residual stress, microstructure evolution and mechanical properties of 7A55 aluminum alloy were investigated by using TEM, EBSD, XRD and micro-hardness tester. The results indicate that the surface stress of the solution treated specimens is compressive, being -75 MPa and -115 MPa along rolling and transversal directions respectively. The residual stress decreases with the increase of pre-strain and almost being eliminated after 2% pre-strain. The subduction rate of residual stress for aging at 180 ℃ is obviously quicker than that at 100 ℃ and 140 ℃. The hardness increases with the increase of pre-strain, and after 3% pre-strain it increases to 92 HV0.5, i.e. by 27.8%. The hardness increases first and then decreases with the increases of aging time, and reaches 135, 143 and 162 HV0.5 respectively when aging at 100, 140 and 180 ℃ for 15 h. When aging at 100 ℃ for 15 h where the peak hardness is obtained, the metastable η′ phase is mainly precipitated inside grains and has a coherent relation with the matrix. When aging at 140 ℃, the size of the intragranular precipitated phase increases, and semi-coherent disk-like η′ phase appears. While aging at 180 ℃, short rod-like η′ phase with a size of 5-20 nm appears, and the grain boundary with small angles (<10°) accounts for more than 80%.

Key words: 7A55 aluminum alloy, residual stress, pre-strain, aging

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