Metallurgical and Mechanical Characterization of High-Speed Friction Stir Welded AA 6082-T6 Aluminum Alloy
by
Anton Naumov 1,*
, Iuliia Morozova 2,*, Evgenii Rylkov 1, Aleksei Obrosov 3, Fedor Isupov 1, Vesselin Michailov 2 and Andrey Rudskoy 1
Anton Naumov 1,*, Iuliia Morozova 2,*, Evgenii Rylkov 1, Aleksei Obrosov 3, Fedor Isupov 1, Vesselin Michailov 2 and Andrey Rudskoy 1
1
Peter the Great St. Petersburg Polytechnic University, 195251 St. Petersburg, Russian
2
Department of Joining and Welding Technologies, Brandenburg University of Technology Cottbus-Senftenberg, 03046 Cottbus, Germany
3
Department of Metallurgy and Materials Technology, Brandenburg University of Technology Cottbus-Senftenberg, 03046 Cottbus, Germany
*
Authors to whom correspondence should be addressed.
Materials 2019, 12(24), 4211; https://doi.org/10.3390/ma12244211
Received: 15 November 2019 / Revised: 6 December 2019 / Accepted: 11 December 2019 / Published: 14 December 2019
(This article belongs to the Special Issue Welding and Joining Processes of Materials)
The objective of this study was to investigate the effect of the high welding speed on the mechanical properties and their relations to microstructural characteristics of butt friction stir welded joints with the use of 6082-T6 aluminum alloy. The aluminum sheets of 2.0 mm thick were friction stir welded at low (conventional FSW) and high welding speeds (HSFSW) of 200 and 2500 mm/min, respectively. The grain size in the nugget zone (NZ) was decreased; the width of the softened region was narrowed down as well as the lowest microhardness value located in the heat-affected zone (HAZ) was enhanced by HSFSW. The increasing welding speed resulted in the higher ultimate tensile strength and lower elongation, but it had a slight influence on the yield strength. The differences in mechanical properties were explained by analysis of microstructural changes and tensile fracture surfaces of the welded joints, supported by the results of the numerical simulation of the temperature distribution and material flow. The fracture of the conventional FSW joint occurred in the HAZ, the weakest weld region, while all HSFSW joints raptured in the NZ. This demonstrated that both structural characteristics and microhardness distribution influenced the actual fracture locations.
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Keywords:
high-speed friction stir welding (HSFSW); aluminum alloy; remnant oxide line (ROL); microstructural characteristics; mechanical properties; fracture behavior; FEM
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MDPI and ACS Style
Naumov, A.; Morozova, I.; Rylkov, E.; Obrosov, A.; Isupov, F.; Michailov, V.; Rudskoy, A. Metallurgical and Mechanical Characterization of High-Speed Friction Stir Welded AA 6082-T6 Aluminum Alloy. Materials 2019, 12, 4211.
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