Journal of South China University of Technology(Natural Science Edition) ›› 2020, Vol. 48 ›› Issue (3): 116-125.doi: 10.12141/j.issn.1000-565X.190402

• Materials Science & Technology • Previous Articles     Next Articles

Microstructure and Corrosion Behavior of 2219 Aluminum Alloy Forging's Joint by TIG Welding

XU Daofen1,2,3 CHEN Kanghua1,4 XING Jun1 CHEN Songyi1 LI Xiaoqian1   

  1. 1. Light Alloy Research Institute, Central South University, Changsha 410083, Hunan, China; 2. School of Mechanical Engineering, Guilin University of Aerospace Technology, Guilin 541004, Guangxi, China; 3. Guangxi Colleges and Universities Key Laboratory of Robot & Welding, Guilin University of Aerospace Technology, Guilin 541004, Guangxi, China; 4. State Key Laboratory of Powder Metallurgy, Central South University, Changsha 410083, Hunan, China
  • Received:2019-07-01 Revised:2019-09-27 Online:2020-03-25 Published:2020-03-01
  • Contact: 陈康华（1962-），男，博士，教授，主要从事铝合金研究。 E-mail:khchen@csu.edu.cn
  • About author:徐道芬（1982-），女，博士生，从事2xxx铝合金及其焊件研究。E-mail:xu_daofeng@126.com
  • Supported by:
    Supported by the National Key Research and Development Program of China (2016YFB0300801), the National Natural Science Foundation of China-China Aerospace Science and Technology Corporation Aerospace Advanced Manufacturing Technology Research Foundation (U1637601), the Major Research Equipment Development Projects of National Natural Science Foundation of China ( 51327902 ), the Opening Project of Guangxi Colleges and Universities Key Laboratory of Robot & Welding (JQR2018ZR02) and the Scientific Research Project of Guangxi Education Department (KY2015ZD141)

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Abstract: 2219 aluminum alloy weldment was prepared by the method of TIG welding. The microstructure evolution and corrosion behavior of 2219 aluminum alloy weldment joint was investigated by optical microscopy (OM), scanning electron microscopy (SEM), transmission electron microscopy (TEM), immersion test and electrochemical corrosion experiment. The results show that the microstructure in the welded zone is dendrites, fine and homogeneous with equiaxed grains. When the corrosion happens, the corrosion potential moves to positive direction and the corrosion resistance increases. The co-existence of residual crystallization phase and continuous grain boundary precipitates in the base metal area, results in the corrosion of the copper poor area around the residual crystalline phase and the grain boundary. Meanwhile, the continuous intergranular phases play a role as channel for electron transfer in the corrosion process, which could accelerate the anodic dissolution rate. All above mentioned factors leaded to the worst corrosion resistance of base metal area. The grain boundary precipitates have discontinuous distribution in the over-aging zone, promoting corrosion potential of grain boundary to shift to a more positive value, which is beneficial to the improvement of corrosion resistance. Lots of Cu-containing supersaturated solid solution and disappearance of precipitate free zones make the corrosion resistance of the quenching zone is superior to that of the over-aging zone. The corrosion resistance of TIG welding joint is different due to the combined action of residual crystalline phases, αAl -matrix, precipitates and grain boundary, which are in the order of welded zone > quenching zone > over-aging zone > base metal.

Key words: 2219 aluminum alloy forging, welded joints, microstructure evolution, corrosion behavior