Influence of ultrasonic vibration on the microstructure and texture evolution of AZ91 magnesium alloy during ultrasonic-assisted friction stir welding

The aim of this work is to investigate the influence of ultrasonic vibration on the microstructure and texture evolution in ultrasonic-assisted friction stir welding (UaFSW) of AZ91 Mg alloy. Ultrasonic vibration with an amplitude of 15 µm induced to the weld line perpendicularly to the welding dire...

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Bibliographic Details
Published in:Welding in the world 2021-12, Vol.65 (12), p.2371-2382
Main Authors: Baradarani, F., Emami, S., Mostafapour, A., MD, F. Khan
Format: Article
Language:English
Subjects:
Chemistry and Materials Science
Dynamic recrystallization
Electron backscatter diffraction
Evolution
Friction stir welding
Grain boundaries
Grain refinement
Magnesium base alloys
Materials Science
Metallic Materials
Microstructure
Research Paper
Solid Mechanics
Statistical analysis
Texture
Theoretical and Applied Mechanics
Ultrasonic vibration
Weld lines
Welded joints
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Summary:The aim of this work is to investigate the influence of ultrasonic vibration on the microstructure and texture evolution in ultrasonic-assisted friction stir welding (UaFSW) of AZ91 Mg alloy. Ultrasonic vibration with an amplitude of 15 µm induced to the weld line perpendicularly to the welding direction. A scanning electron microscopy equipped with electron backscattered diffraction (EBSD) was used to investigate the microstructure and texture changes of the joints. A high fraction of low-angle grain boundaries (LAGBs) was observed during the occurrence of dynamic recovery (DRV) in thermomechanically affected zones (TMAZs) of welded specimens. Statistical analysis from the grain boundaries of the stir zone (SZ) revealed that the fraction of high-angle grain boundaries (HAGBs) in the SZ of UaFSW joint is higher than that of the FSW joint. The results along with the formation of simple shear texture components in the SZ of welds imply that continuous dynamic recrystallization (CDRX) is responsible for grain refinement in the SZs. Moreover, vibration associated with UaFSW assisted the DRV and CDRX mechanisms and increases the intensity of the developed texture in the SZ of the UaFSW joint.
ISSN:0043-2288
1878-6669
DOI:10.1007/s40194-021-01157-5