Effects of nano-Al2O3 particle addition on grain structure evolution and mechanical behaviour of friction-stir-processed Al

The “stop-action” technique was employed to study grain structure evolution during friction-stir welding of AZ31 magnesium alloy. The grain structure formation was found to be mainly governed by the combination of the continuous and discontinuous recrystallization but also involved geometric effect of strain and local grain boundary migration. Orientation measurements showed that the deformation mode was very close to the simple shear associated with the rotating pin and material flow arose mainly from basal slip.

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Application of Imaging Techniques to Determine the Post-Yield Behaviour of the Heterogeneous Microstructure of Friction Stir Welds

Experimental Mechanics ◽

10.1007/s11340-021-00722-9 ◽

2021 ◽

Author(s):

S. Ramachandran ◽

A. K. Lakshminarayanan ◽

P. A. S. Reed ◽

J. M. Dulieu-Barton

Keyword(s):

Tool Wear ◽

Mechanical Behaviour ◽

Base Material ◽

Grain Morphology ◽

Stir Zone ◽

Image Correlation ◽

Grain Structure ◽

Weld Nugget ◽

Heterogeneous Microstructure ◽

Friction Stir

Abstract Background Friction Stir Welding (FSW) causes intense plastic deformation and consequent thermomechanical interactions resulting in a localised heterogeneous microstructure. To understand the weld mechanical behaviour, it is necessary to identify each microstructural sub-region in the weld. Objective Determine the relationship between the local microstructure and mechanical behaviour of the different microstructural regions in a FSW. Methods Scanning electron microscopy (SEM) identified the microstructural sub-regions of an FSW joint. A novel High-Resolution Digital Image Correlation (HR-DIC) methodology enabled the determination of full-field strain response to provide the mechanical behaviour of the FSW sub-regions. X-ray computed tomography (CT) identified the geometry of the FSW and material composition. Results The grain morphology in the FSW varied in the stir zone with a fine grain structure in the weld nugget and larger grains in the thermomechanical affected zone (TMAZ); the grains were larger in the retreating side (RS) compared to the advancing side (AS). Tungsten deposits were found in the weld nugget and attributed to tool wear. The mechanical properties of the weld subregions showed that the material in the stir zone had a greater yield strength than the base material and the RS of the FSW was much more ductile than the weld nugget and the AS side. The tungsten distributions in the stir zone correlated with the local mechanical behaviour. Conclusions A novel methodology is developed that combines microstructural observations with HR-DIC enabling, for the first time, the FSW sub-region mechanical behaviour, to be related to the local grain morphology and inclusions caused by tool wear.

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Analysis and characterization of dynamic recrystallization and grain structure evolution in friction stir welding of aluminum plates

Acta Materialia ◽

10.1016/j.actamat.2021.116692 ◽

2021 ◽

Vol 207 ◽

pp. 116692

Author(s):

Pengfei Yu ◽

ChuanSong Wu ◽

Lei Shi

Keyword(s):

Friction Stir Welding ◽

Dynamic Recrystallization ◽

Grain Structure ◽

Structure Evolution ◽

Friction Stir ◽

Aluminum Plates

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Grain structure evolution during friction-stir welding of AZ31 magnesium alloy

Acta Materialia ◽

10.1016/j.actamat.2009.07.041 ◽

2009 ◽

Vol 57 (18) ◽

pp. 5406-5418 ◽

Cited By ~ 161

Author(s):

U.F.H.R. Suhuddin ◽

S. Mironov ◽

Y.S. Sato ◽

H. Kokawa ◽

C.-W. Lee

Keyword(s):

Friction Stir Welding ◽

Magnesium Alloy ◽

Grain Structure ◽

Az31 Magnesium Alloy ◽

Structure Evolution ◽

Friction Stir

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Nanoindentation Hardness Distribution and Strain Field and Fracture Evolution in Dissimilar Friction Stir-Welded AA 6061-AA 5A06 Aluminum Alloy Joints

Advances in Materials Science and Engineering ◽

10.1155/2018/4873571 ◽

2018 ◽

Vol 2018 ◽

pp. 1-11 ◽

Cited By ~ 9

Author(s):

Guangjian Peng ◽

Yi Ma ◽

Jiangjiang Hu ◽

Weifeng Jiang ◽

Yong Huan ◽

...

Keyword(s):

Mechanical Properties ◽

Aluminum Alloy ◽

Strain Field ◽

Optical Microscope ◽

Image Correlation ◽

Grain Structure ◽

Structure Evolution ◽

Hardness Distribution ◽

Slant Angle ◽

Friction Stir

Aluminum alloy AA 6061-T651 and 5A06-H112 rolled plates were successfully welded by friction stir welding (FSW) at three rotation speeds of 600, 900, and 1200 rpm with two transverse speeds of 100 and 150 mm/min. Mechanical properties and strain field evolution of FSW AA 6061-AA 5A06 were characterized by the uniaxial tension and digital image correlation (DIC) tests. Furthermore, the hardness distribution map of whole cross section was obtained via the nanoindentation method with 700 indents. Both DIC and nanoindentation results reveal that the heat-affected zone (HAZ) of AA 6061 alloy is the softest area in the weldment, and the fracture happens in this region. The microstructure evolution characterized by electron-backscatter diffraction (EBSD) indicates that the continuous dynamic recrystallization is the primary grain structure evolution in the stirring zone, and the grain refinement helps improve the mechanical properties. Analyses of the micro- and macrofeatures of the fracture surfaces via scanning electron microscopy (SEM) and optical microscope suggest that the increasing of heat input could enlarge the size of HAZ and reduce the slant angle of HAZ and thus lead the fracture angle to decrease and cause the dimples change from inclined ones to normal ones.

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