| 1. |
- Zhang, Chenghang, et al.
(författare)
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Characterizations of microstructure, crystallographic texture and mechanical properties of dissimilar friction stir welding joints for AA2024 and AA7075 under different tool shoulder end profiles
- 2020
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Ingår i: Materials Today Communications. - : Elsevier Ltd. - 2352-4928. ; 25, s. 101435-
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Tidskriftsartikel (refereegranskat)abstract
- In this investigation, the influence of tool shoulder end profiles (concentric circle shoulder-CCS and three-helix shoulder-THS) and rotational speed (ROSP, 800, 1100, 1400 rpm) on microstructure and mechanical performance of the dissimilar FSW AA2024/7075 joints was analyzed in detail. The results indicated that the width of thermos-mechanical affected zone and the average grain size of nugget zone (NZ) in the CCS joints are lower than those in the THS joints, and they all increase with increasing the ROSP. There is a difference on the shear texture types generated in the different positions of the NZ in the CCS and THS joints. Tensile properties of the joints fabricated by employing the CCS tool are excellent compared to the THS tool. The maximum welding efficiency about 90.8 % can be obtained in the CCS joint at 1000 rpm. The fracture mode of the CCS and THS joints is ductile and brittle failure, respectively.
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| 2. |
- Zhang, Chenghang, et al.
(författare)
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Investigation on microstructure and localized corrosion behavior in the stir zone of dissimilar friction-stir-welded AA2024/7075 joint
- 2020
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Ingår i: Journal of Materials Science. - : Springer. - 0022-2461 .- 1573-4803. ; 55:30, s. 15005-15032
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Tidskriftsartikel (refereegranskat)abstract
- Friction stir welding (FSW) is an effective welding technique to realize the joining of dissimilar aluminum alloys. The microstructural heterogeneities induced by FSW across the joints could have curial implication for the corrosion performance of the joints. In this research, the microstructure and localized corrosion behavior of shoulder interface zone (SIZ), vortex zone (VZ), bottom zone (BZ) and bottom interface zone (BIZ) in the stir zone (SZ) of dissimilar FSW AA2024/AA7075 joint was systematically investigated through detailed microstructural characterization and relevant corrosion tests. The results indicated that plentiful of Cu-rich constituent particles are formed on AA2024 side and the areas near the interface on both sides, and corrosion originates from these regions. Grain size has little influence on corrosion behavior of the SZ, while the local regions with higher stored energy are more sensitive and liable to corrosion. The sequence of mixing degree of materials in the four regions of the SZ is: BZ > VZ > SIZ > BIZ, which is in contrast to the order of corrosion rate. Galvanic corrosion is detected in the SIZ and BIZ, and sufficient mixing of materials significantly weakens the galvanic corrosion, resulting in higher corrosion resistance in the BZ.
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