The effect of postprocessing on tensile property and microstructure evolution of friction stir welding aluminum alloy joint

Journal Article · Thu Jan 15 04:00:00 EST 2015 · Materials Characterization

DOI:https://doi.org/10.1016/J.MATCHAR.2014.11.015· OSTI ID:22476017

Wang, X. S. ^[1]; Pang, Q. ^[2]; Huang, F.; Qin, X. P.; Hua, L. ^[3]

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1. State Key Laboratory of Advanced Welding and Joining, Harbin Institute of Technology, Harbin 150001 (China)
2. School of Mechanical and Electrical Engineering, Wuhan Donghu University, Wuhan 430070 (China)
3. Hubei Key Laboratory of Advanced Technology of Automobile Parts, Wuhan University of Technology, Wuhan 430070 (China)

Friction stir welding is an efficient manufacturing method for joining aluminum alloy and can dramatically reduce grain size conferring excellent plastic deformation properties. Consequently, friction stir welding is used to manufacture tailor welded blanks to optimize weight or performance in the final component. In the study, the microstructural evolution and mechanical properties of friction stir welding joint during plastic forming and subsequent heat treatment were investigated. The microstructural characteristics of the friction stir welding joints were studied by Electron Backscattered Diffraction and Transmission Electron Microscopy. The mechanical properties were evaluated by tensile and microhardness tests. It is found that the tensile and yield strengths of friction stir welding joints are significantly improved after severe plastic deformation due to the grain refinement. Following heat treatment, the strength of the friction stir welding joints significantly decrease due to the obvious abnormal grain growth. Careful attention must be given to the processing route of any friction stir welding joint intended for plastic forming, especially the annealing between forming passes. Severe plastic deforming of the friction stir welding joint leads to a high level of stored energy/dislocation density, which causes the abnormal grain growth during subsequent heat treatment, and consequently reduce the mechanical properties of the friction stir welding joint. - Highlights: • Great changes are observed in the microstructure of FSW joint after postprocessing. • Postprocessing shows great effect on the microstructure stability of FSW joint. • The weld shows more significant decrease in strength than the BM due to the AGG. • Attention must be given to the processing route of FSW joint for plastic forming.

• OSTI ID: 22476017
• Journal Information: Materials Characterization, Journal Name: Materials Characterization Vol. 99; ISSN 1044-5803; ISSN MACHEX
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
ALUMINIUM ALLOYS
ANNEALING
DENSITY
DIFFRACTION
DISLOCATIONS
FRICTION
GRAIN GROWTH
GRAIN REFINEMENT
GRAIN SIZE
MICROHARDNESS
PERFORMANCE
PLASTICITY
STABILITY
STORED ENERGY
TRANSMISSION ELECTRON MICROSCOPY
WELDED JOINTS
WELDING
YIELD STRENGTH