J. Mater. Sci. Technol. ›› 2018, Vol. 34 ›› Issue (1): 228-236.DOI: 10.1016/j.jmst.2017.11.039

Special Issue: Aluminum Alloys-2018 FSW-and-FSP-articles 2018

• Orginal Article • Previous Articles     Next Articles

Inhomogeneity of microstructure and mechanical properties in the nugget of friction stir welded thick 7075 aluminum alloy joints

Yuqing Mao*(), Liming Ke, Yuhua Chen, Fencheng Liu, Li Xing   

  1. National Defence Key Discipline Laboratory of Light Alloy Processing Science and Technology, Nanchang Hangkong University, Nanchang 330063, China
  • Received:2017-04-10 Revised:2017-07-10 Accepted:2017-07-18 Online:2018-01-20 Published:2018-02-09
  • Contact: Mao Yuqing

Abstract:

In this study, 20 mm thick AA7075-T6 alloy plates were joined by friction stir welding. The microstructure and mechanical properties of the nugget zone along the thickness direction from the top to the bottom was investigated. The results showed that the microstructure including the grain size, the degree of dynamic recrystallization, the misorientation angle distribution and the precipitation phase containing its size, type and content exhibited a gradient distribution along the thickness direction. The testing results of mechanical properties of the slices showed that the nugget was gradually weakened along the depth from the top to the bottom. The maximum ultimate tensile strength, yield strength and elongation of the slice in the nugget top-middle are obtained, which are 415 MPa, 255 MPa and 8.1%, respectively.

Key words: AA7075 thick plate, Friction stir welding, Nugget, Heterogeneity, Microstructure, Mechanical properties