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双级时效对7050-T7451铝合金搅拌摩擦焊组织及应力腐蚀敏感性的影响

张华, 郭启龙, 赵常宇, 林三宝, 石功奇

张华, 郭启龙, 赵常宇, 林三宝, 石功奇. 双级时效对7050-T7451铝合金搅拌摩擦焊组织及应力腐蚀敏感性的影响[J]. 焊接学报, 2020, 41(6): 1-5. DOI: 10.12073/j.hjxb.20190513001
引用本文: 张华, 郭启龙, 赵常宇, 林三宝, 石功奇. 双级时效对7050-T7451铝合金搅拌摩擦焊组织及应力腐蚀敏感性的影响[J]. 焊接学报, 2020, 41(6): 1-5. DOI: 10.12073/j.hjxb.20190513001
ZHANG Hua, GUO Qilong, ZHAO Changyu, LIN Sanbao, SHI Gongqi. Influence of two-step aging on structure and stress corrosion sensitivity of friction stir welded 7050-T7451 aluminum alloys[J]. TRANSACTIONS OF THE CHINA WELDING INSTITUTION, 2020, 41(6): 1-5. DOI: 10.12073/j.hjxb.20190513001
Citation: ZHANG Hua, GUO Qilong, ZHAO Changyu, LIN Sanbao, SHI Gongqi. Influence of two-step aging on structure and stress corrosion sensitivity of friction stir welded 7050-T7451 aluminum alloys[J]. TRANSACTIONS OF THE CHINA WELDING INSTITUTION, 2020, 41(6): 1-5. DOI: 10.12073/j.hjxb.20190513001

双级时效对7050-T7451铝合金搅拌摩擦焊组织及应力腐蚀敏感性的影响

基金项目: 国家自然科学基金资助项目(51774047);北京市长城学者培养计划(CIT&TCD20170309).
详细信息
    作者简介:

    张华,1976年出生,博士,教授;主要从事搅拌摩擦焊、腐蚀与防护方面研究;发表论文40余篇; Email:huazhang@bipt.edu.cn.

  • 中图分类号: TG 453+.9

Influence of two-step aging on structure and stress corrosion sensitivity of friction stir welded 7050-T7451 aluminum alloys

  • 摘要: 采用搅拌摩擦焊方法对3 mm厚7050-T7451铝合金进行焊接,为改善接头应力腐蚀敏感性,焊后进行121 ℃ × 5 h + 163 ℃ × 27 h双级时效处理. 通过对微观组织、显微硬度以及应力腐蚀敏感性的分析,研究双级时效对焊接接头性能的影响. 结果表明,双级时效后晶粒发生粗化,晶界内析出相和周边无沉淀析出带(PFZ)变宽,导致在热影响区和热力影响区出现大量不连续晶界;接头热影响区的显微硬度有所下降,但范围明显变窄,接头组织的均一性得到改善;时效处理后的接头在进行应力腐蚀试验 60天后仍未发生断裂,而未经时效处理的接头在1天内全部发生断裂,说明双级时效有效降低了焊接接头的应力腐蚀敏感性.
    Abstract: 3 mm thick 7050-T7451aluminum alloy joint was obtained by friction stir welding, and the two-stage aging treatment was performed at 121 ℃ × 5 h + 163 ℃ × 27 h after welding. Microstructure, hardness profiles and stress corrosion sensitivity of the joint were measured and studied. The results indicate that through the two-step aging, the grain size is coarsened, the age-hardening precipitates and PFZ become wider at the same time, which results in the discontinuous grain boundary; the microhardness of the FSW joints decreased, but the heat-affected zone significantly narrowed, which increased the uniformity of the microhardness of the FSW joints; and the two-stage aging effectively reduced the stress corrosion sensitivity of the FSW joints. The joints with aging treatment were not broken after 60 days, however all the joints without aging treatment were broken within 1 day.
  • 图  1   四点弯曲试样装配图

    Figure  1.   Assembly drawing of four-point bending

    图  2   AA7050 焊接接头时效处理前后组织形貌

    Figure  2.   Organization morphologies before and after aging treatment of AA7075 welding joint. (a) before aging treatment welding nugget zone; (b) after aging treatment welding nugget zone; (c) before aging treatment thermal-mechanical affect zone; (d) after aging treatment thermal-mechanical affect zone; (e) before aging treatment heat affected zone; (f) after aging treatment heat affected zone

    图  3   时效处理前后晶界结构模型图

    Figure  3.   Grain boundary structure model before and after aging treatment. (a) before aging treatment; (b) after aging treatment

    图  4   时效处理前后焊接接头硬度分布

    Figure  4.   Microhardness profile before and after aging treatment of welded joint

    图  5   焊态及时效处理后接头应力腐蚀形貌

    Figure  5.   Stress corrosion morphologies of as-welded and aging treatment of welded joint. (a) as-welded; (b) aging treatment

    图  6   时效处理后接头腐蚀截面图

    Figure  6.   Cross section of welded joint after aging treatment. (a) welding nugget zone; (b) thermal-mechaincal affeect zone; (c) heat affected zone

    表  1   7050-T7451铝合金化学成分(质量分数,%)

    Table  1   Chemical compositions of 7050-T7451 Al alloy

    ZnMgCuFeSiZrMnTiCrVAl
    6.12.22.10.090.060.090.010.040.010.01余量
    下载: 导出CSV

    表  2   7050-T7451铝合金力学性能

    Table  2   Mechanical properties of 7050-T7451 Al alloy

    抗拉强度Rm/MPa屈服强度Rp0.2/MPa断后伸长率A(%)
    534.547212.8
    下载: 导出CSV
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出版历程
  • 收稿日期:  2019-05-12
  • 网络出版日期:  2020-09-26
  • 刊出日期:  2020-09-26

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