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Microstructure and Stress Corrosion Behavior of MIG Welded Joint Al–Zn–Mg Alloy

  • Lingying Ye
  • Wenqing Yang
  • Chuqi Jiang
  • Huaqiang Lin
  • Shengdan Liu
  • Jianguo Tang
  • Yunlai Deng
  • Xinming Zhang
Conference paper

Abstract

The microstructures and stress corrosion behaviors of the welded joint in a MIG welded Al–Zn–Mg alloy were investigated by slow strain rate test and OM, EBSD, TEM observation. The results indicated that the stress corrosion cracking index of welded joint is bigger than the base metal, which means the stress corrosion resistance of base metal is better than MIG welded joint. The stress corrosion of MIG welded joints mainly occur in the weld zone and heat affected zone, which indicates that they are the weak areas of welded joints. The fracture mode of the joint in 3.5% NaCl solution are intergranular brittle fracture and partial transgranular dimple fracture, while that of base metal is only transgranular dimple fracture. The microstructure is coarse equiaxed grain in welded zone, and there is virtually no strengthening phase in this zone. In the fusion zone, fine columnar grains and equiaxed grains are distributed at different sides. There is the fibrous phase in the base metal, and the microstructure of heat affected zone is similar to this zone. But in the heat affected zone, recrystallization occurs and the grains grow obviously. And the strengthening phases in the quenching zone are completely dissolved, but their particles in over aged zone became coarseobviously.

Keywords

Al–Zn–Mg alloy MIG welded joint Stress corrosion behavior Microstructure 

Notes

Acknowledgements

This work is funded by the National Basic Research Program of China (2012CB619500), the Major State Research Program of China (2016YFB0300901), the National Natural Science Foundation of China (51375503), the Scientific Research and Technology Development Program of Guangxi (AA16380036) and the BaGui Scholars Program of China’s Guangxi Zhuang Autonomous Region (2013A017).

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Copyright information

© Springer Nature Singapore Pte Ltd. 2018

Authors and Affiliations

  • Lingying Ye
    • 1
    • 2
    • 3
  • Wenqing Yang
    • 1
    • 2
  • Chuqi Jiang
    • 1
  • Huaqiang Lin
    • 1
    • 4
  • Shengdan Liu
    • 1
    • 2
  • Jianguo Tang
    • 1
    • 2
  • Yunlai Deng
    • 1
    • 2
  • Xinming Zhang
    • 1
    • 2
  1. 1.School of Materials Science and EngineeringCentral South UniversityChangshaChina
  2. 2.Collaborative Innovation Center of Advanced Nonferrous Structural Materials and ManufacturingChangshaChina
  3. 3.Guangxi Liuzhou Yinhai Aluminum Co., Ltd.LiuzhouChina
  4. 4.National Engineering Research Center for High-Speed EMU, CRRC Qingdao Sifang Co., Ltd.QingdaoChina

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