金属热处理 ›› 2021, Vol. 46 ›› Issue (7): 173-177.DOI: 10.13251/j.issn.0254-6051.2021.07.033

• 工艺研究 • 上一篇    下一篇

时效处理对7A20铝合金时效硬化响应和晶间腐蚀的影响

王珊1, 王淑慧1, 刘文文1,2, 滕敦波1, 张日强3, 王旭强1, 向康宁1   

  1. 1.烟台南山学院 工学院, 山东 烟台 265713;
    2.烟台南山学院 山东省高校轻合金加工成形重点实验室, 山东 烟台 265713;
    3.山东南山铝业股份有限公司板带事业部 国家铝合金压力加工工程技术研究中心, 山东 烟台 265706
  • 收稿日期:2021-02-06 出版日期:2021-07-25 发布日期:2021-12-10
  • 作者简介:王 珊(1979—),女,讲师,硕士,主要研究方向为金属材料的组织与性能,E-mail: freeheart33@163.com。
  • 基金资助:
    山东省高等学校青创科技计划(2019KJA019)

Influence of aging treatment on hardening response and intergranular corrosion of 7A20 aluminum alloy

Wang Shan1, Wang Shuhui1, Liu Wenwen1,2, Teng Dunbo1, Zhang Riqiang3, Wang Xuqiang1, Xiang Kangning1   

  1. 1. College of Engineering, Yantai Nanshan University, Yantai Shandong 265713, China;
    2. Key Laboratory of Light Alloy Processing and Forming of Shandong Universities, Yantai Nanshan University, Yantai Shandong 265713, China;
    3. National Engineering Research Center for Plastic Working of Aluminum Alloys, Flat-Rolled Product Division of Shandong Nanshan Aluminum Industry Plate Belt Business Unit,Yantai Shandong 265706, China
  • Received:2021-02-06 Online:2021-07-25 Published:2021-12-10

摘要: 研究了自然时效(NA)效应对7A20铝合金人工时效硬化行为的影响,测试了其维氏硬度和力学性能,运用金相显微镜、扫描电镜和透射电镜表征了其微观组织演变情况。结果表明:固溶处理后的试样在室温放置过程中表现出明显的自然时效效应。经3天(NA3)和8天(NA8)自然时效处理后的试样,人工时效初期均出现了时效软化效应,经2 h人工时效后,显微硬度分别降低25.3%和22.7%。不同热处理后试样的基体晶粒无明显差异,但晶内结构却有明显差别。热处理后的试样,在晶界处均存在20 nm左右的PFZ区。NA3+160 ℃×40 h和NA8+160 ℃×40 h的试样,晶内短棒状析出相数量增多。固溶处理后直接进行人工时效,抗晶间腐蚀性能最好,腐蚀深度为80~120 μm。NA3和NA8试样经160 ℃×40 h人工时效后,其晶间腐蚀深度分别达到了100~140 μm和120~160 μm,且有明显的脱落现象。

关键词: 7A20铝合金, 自然时效, 组织演变, 晶间腐蚀

Abstract: Influence of natural aging(NA) on artificial aging hardening behavior of the 7A20 aluminum alloy was investigated. The Vickers hardness and mechanical properties were tested. The microstructure evolution was characterized by means of OM, SEM and TEM. The results indicate that the specimens after solution treatment have obvious natural aging effect during the natural placed process. The softening effect is observed during the artificial aging treatment after NA for 3 days(NA3) and 8 days(NA8) and the micro-hardness decreases 25.3% and 22.7% respectively after 2 h AA treatment. The grain size has no obvious difference after different heat treatments, while the inner grain structure has obvious difference. PFZ zone with about 20 nm width exists at grain boundaries of all the specimens after heat treatment. The fraction of the rod-like precipitation phase in crystals of the specimens of NA3+160 ℃×40 h and NA8+160 ℃×40 h is increased. The specimen under artificial aging directly after solution treatment has the best resistance to intergranular corrosion, its corrosion depth is 80-120 μm, while the specimens of NA3+160 ℃×40 h and NA8+160 ℃×40 h have the intergranular corrosion depth of 100-140 μm and 120-160 μm, respectively, and have obviously peeled off phenomenon.

Key words: 7A20 aluminum alloy, natural aging, microstructure evolution, intergrannular corrosion

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