Microstructure and mechanical properties of spot friction stir welded ultrafine grained 1050 Al and conventional grained 6061-T6 Al alloys

Recently, several metallic materials with ultrafine-grained structures and characterized by high strength and toughness have been developed. When these ultrafine-grained materials are practically used, welding and joining processes are required. However, conventional fusion welding processes result in deterioration of the good mechanical properties of these ultrafine-grained materials due to the drastic grain growth of the ultrafine grains. On the other hand, friction stir welding (FSW) is a solid-state joining process having lower heat-input than fusion welding processes, enabling formation of a fine grain structure in the stir zone. Thus, this process would effectively alleviate deterioration of mechanical properties of the ultrafine-grained materials. The authors applied FSW to ultrafine-grained Al alloys and then examined the microstructural features associated with hardness in the friction stir welds. The present paper reviews microstructural evolution of ultrafine-grained Al alloys, produced by equal channel angular pressing (ECAP) and accumulative roll-bonding (ARB), during FSW.

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Microstructure and mechanical properties of friction stir welded joints made from ultrafine grained aluminium 1050

Materials & Design ◽

10.1016/j.matdes.2015.08.129 ◽

2015 ◽

Vol 88 ◽

pp. 22-31 ◽

Cited By ~ 27

Author(s):

Marta Lipińska ◽

Lech Olejnik ◽

Adam Pietras ◽

Andrzej Rosochowski ◽

Piotr Bazarnik ◽

...

Keyword(s):

Mechanical Properties ◽

Welded Joints ◽

Friction Stir ◽

Microstructure And Mechanical Properties ◽

Ultrafine Grained

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Effect of rotational speeds on microstructure and mechanical properties of friction stir-welded 7075-T6 aluminium alloy

Proceedings of the Institution of Mechanical Engineers Part C Journal of Mechanical Engineering Science ◽

10.1177/0954406211404633 ◽

2011 ◽

Vol 225 (8) ◽

pp. 1761-1773 ◽

Cited By ~ 8

Author(s):

H Rezaei ◽

M H Mirbeik ◽

H Bisadi

Keyword(s):

Mechanical Properties ◽

Plastic Deformation ◽

Rotational Speed ◽

Thermal Cycle ◽

Al Alloys ◽

Friction Stir ◽

Microstructure And Mechanical Properties ◽

Average Grain Size ◽

Weld Properties ◽

Rotary Speed

In this article, effects of rotational speed on the microstructure and mechanical properties of friction stir-welded 7075-T6 Al alloys were investigated. Good correlation existed between the rotational speeds and weld properties. It was found that with increase in the rotational speed, higher pick temperatures and wider thickness of the heat-affected zone were obtained, and then grain coarsening, dissolution, and accumulation of hardening precipitates in grain boundaries. The average grain size of nugget increased from 6.8 to 8.9 µm, with increasing rotary speed from 600 to 1550 r/min. In addition, the best mechanical properties were obtained at moderate rotational speed of 825 r/min while ultimate tensile strength and elongation were 405 MPa and 6.1 per cent, respectively. Also, it was observed that at low welding speed of 60 mm/min, the weld properties are found to be dominated by the thermal cycle rather than the plastic deformation induced by tool, so as to make a reduction in hardness and strength of the weld when using higher rotational speeds.

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