Metallurgical and Mechanical Characterization of High-Speed Friction Stir Welded AA 6082-T6 Aluminum Alloy

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 w...

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Bibliographic Details
Published in:Materials 2019-12, Vol.12 (24), p.4211
Main Authors: Naumov, Anton, Morozova, Iuliia, Rylkov, Evgenii, Obrosov, Aleksei, Isupov, Fedor, Michailov, Vesselin, Rudskoy, Andrey
Format: Article
Language:English
Subjects:
Alloys
Aluminum alloys
Aluminum base alloys
Butt joints
Elongation
Fracture surfaces
Friction stir welding
Grain size
Heat affected zone
Mechanical properties
Metal sheets
Metallurgy
Microhardness
Shear stress
Temperature distribution
Ultimate tensile strength
Welded joints
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Summary: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.
ISSN:1996-1944
1996-1944
DOI:10.3390/ma12244211