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Materials 2018, 11(7), 1156; https://doi.org/10.3390/ma11071156

Fabrication and Mechanical Properties of Tungsten Inert Gas Welding Ring Welded Joint of 7A05-T6/5A06-O Dissimilar Aluminum Alloy

1
School of Mechanical Engineering, Northwestern Polytechnical University, 127 Youyi Ave. West, Xi’an 710072, China
2
Kunming Precision Machinery Research Institute, P.O. Box No. 26, Kunming 650118, China
3
College of Naval Architecture and Ocean Engineering, Naval University of Engineering, P.O. Box No. 076, Wuhan 430033, China
*
Authors to whom correspondence should be addressed.
Received: 3 June 2018 / Revised: 27 June 2018 / Accepted: 28 June 2018 / Published: 6 July 2018
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Abstract

In this paper, Tungsten Inert Gas Welding (TIG) and single-sided welding and double-sided forming have been used to weld the 7A05-T6/5A06-O dissimilar aluminum alloy circular welded joint of a ring-stiffened closed cylindrical sandwich shell. Microstructural characterization and mechanical properties of welded joints were investigated by use of scanning electron microscopy (SEM), backscatter electron diffraction (EBSD) and transmission electron microscopy (TEM), respectively. Hardness distribution and tensile properties of the welded joints were examined. The results showed the failure of the welded joints produced in the fusion zone (FZ). The tensile strength and yield strength of the welded joints were, respectively, 78.87% and 97.24% of the 5A06-O base metal (BM), and the elongation reached 84.29% of 7A05-T6 base metal. Welding high heat input led to the coarse grain size in the fusion zone, and the long-term similar quenching effect can lead to the full dissolution of the strengthening zone of the fusion zone resulting in the reductions of strength and hardness. Around 7A05 heat-affected zone (HAZ), there is an obvious hardening zone and softening zone, the solid solution precipitates into the Rayleigh brilliant η′ (MgZn2) phase, which results in natural aging strengthening, thus obtaining high hardness. η′ (MgZn2) enhanced phase dissolved fully and the dislocation density decreased rapidly in the HAZ region resulted in a softening zone with a lower hardness at about (10–18) mm from the center of the weld center. View Full-Text
Keywords: TIG welding; similar quenching effect; heat-affected zone; Aluminum alloys; heat input; microstructural characterization TIG welding; similar quenching effect; heat-affected zone; Aluminum alloys; heat input; microstructural characterization
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This is an open access article distributed under the Creative Commons Attribution License which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. (CC BY 4.0).
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Wang, W.; Cao, Z.; Liu, K.; Zhang, X.; Zhou, K.; Ou, P. Fabrication and Mechanical Properties of Tungsten Inert Gas Welding Ring Welded Joint of 7A05-T6/5A06-O Dissimilar Aluminum Alloy. Materials 2018, 11, 1156.

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