Microstructure and mechanical properties of friction stir welded AA6092/SiC metal matrix composite

Salih, Omar S.; Ou, Hengan; Wei, Xingguo; Sun, W.

Abstract

There is a need for improved understanding on the effects of friction stir welding (FSW) on the metallurgical and mechanical properties of aluminium matrix composite (AMC). In this study, AA6092/SiC/17.5p-T6 AMC joints were produced by using FSW with varying tool rotation and traverse speeds. The microstructural characterisation by scanning electron microscopy equipped with electron backscattered diffraction (EBSD) system revealed a substantial grain refinement and a homogeneous distribution of reinforcement particles in the nugget zone. The grain size of the nugget zone was greatly influenced by weld pitch, as a key indicator to control the amount of heat input, exposure time and cooling rate. Vickers microhardness profile across the welding zone revealed a significant difference in microhardness among the base metals, heat affected zone, thermo-mechanically affected zone and nugget zone. The tensile strength of the cross-weld specimens showed a high joint efficiency of about 75% of the base metal combined with relatively high ductility. Low-cycle fatigue properties were investigated in the axial total strain-amplitude control mode (from 0.3% to 0.5%) with 𝑅=𝜀𝑚𝑖𝑛𝜀𝑚𝑎𝑥=−1⁄. The results indicate that the fatigue life of the cross-welded joints varies with grain size in the nugget zone and it is lower than that of the base metal. A significant improvement of fatigue life is found to be related to the finer equiaxed grains dominated by high angle grain boundaries in the nugget zone.

Citation

Salih, O. S., Ou, H., Wei, X., & Sun, W. (2019). Microstructure and mechanical properties of friction stir welded AA6092/SiC metal matrix composite. Materials Science and Engineering: A, 742, 78-88. https://doi.org/10.1016/j.msea.2018.10.116

• Journal Article Type: Article
• Acceptance Date: Oct 28, 2018
• Online Publication Date: Nov 1, 2018
• Publication Date: Jan 10, 2019
• Deposit Date: Nov 8, 2018
• Publicly Available Date: Nov 2, 2019
• Journal: Materials Science and Engineering: A
• Print ISSN: 0921-5093
• Electronic ISSN: 0921-5093
• Publisher: Elsevier
• Peer Reviewed: Peer Reviewed
• Volume: 742
• Pages: 78-88
• DOI: https://doi.org/10.1016/j.msea.2018.10.116
• Public URL: https://nottingham-repository.worktribe.com/output/1235712
• Publisher URL: https://www.sciencedirect.com/science/article/pii/S0921509318315077
• Additional Information: This article is maintained by: Elsevier; Article Title: Microstructure and mechanical properties of friction stir welded AA6092/SiC metal matrix composite; Journal Title: Materials Science and Engineering: A; CrossRef DOI link to publisher maintained version: https://doi.org/10.1016/j.msea.2018.10.116; Content Type: article; Copyright: © 2018 The Authors. Published by Elsevier B.V.