Journal of Northeastern University ›› 2006, Vol. 27 ›› Issue (1): 49-52.DOI: -

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Microstructure and properties of welded joints on Al-alloy sheets for high-speed train carriages

Tian, Fu-Quan (1); Fu, Gao-Feng (1); Zhou, Chuan-Liang (2); Jiang, Lan (1)   

  1. (1) School of Materials and Metallurgy, Northeastern University, Shenyang 110004, China; (2) Jiaozuo Wanfang Aluminum Co. Ltd., Jiaozuo 454003, China
  • Received:2013-06-23 Revised:2013-06-23 Online:2006-01-15 Published:2013-06-23
  • Contact: Tian, F.-Q.
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Abstract: The microstructure and mechanical properties of the joints welding domestic 7020 Al-alloy sheets together by use of metal inert gas (MIG) were investigated. It was found that the hardness distribution is symmetrical to the center line of welded joint, where is just the weakest zone of the whole joint to which the weld zone presents a typical dendritic casting structure. In the fusion zone, the columnar grains range in the direction of heat dissipation on one side of the joint and fine equiaxed grains on the other side. Fibrous processing marks remain in the heat-affected zone (HAZ) with part of precipitated solid phase solved into the base metal. Precipitate microstructure shows that the growth of precipitates is the main reason to soften the HAZ. The results showed that the tensile strength of the joints welding the 7020 Al-alloy sheets together exceeds the standard DIN EN288-4.

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