Superplastic deformation behaviour of friction stir processed 7075Al alloy

Cast Mg-4.27Y-2.94Nd-0.51Zr (wt.%) alloy was subjected to submerged friction stir processing (SFSP) with at a rotation rate of 600 rpm and a traveling speed of 60 mm min-1. Superplastic behavior of specimens with an average grain size of ~1.3 μm were investigated in the temperature ranges of 683-758 K and the strain rate ranges from 1×10-1 to 4×10-4 s-1. Microstructure characteristics were investigated by optical microscopy, scanning electron microscopy and transmission electron microscopy. The results show that the maximum elongation of 967% was obtained at 733 K and 3×10-3 s-1, the optimal HSRS of 900% achieved at 758 K and 2×10-2 s-1. Grains and second phase particles grew coarser with the increasing temperature or decreasing strain rate. Remarkable grain growth is the main reason that elongations are all significantly decreased when the strain rate decrease from 3×10-3 s-1 to 4×10-4 s-1. Grain boundary sliding is the main mechanism during superplastic deformation.

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Superplastic Deformation and Microstructure Evolution of Friction Stir Weld of 1420 Al-Li Alloy

Materials Science Forum - PRICM-5 ◽

10.4028/0-87849-960-1.3033 ◽

2005 ◽

pp. 3033-3036

Author(s):

He Ping Guo ◽

Xiuquan Han ◽

Wei Wu ◽

Zhi Qiang Li

Keyword(s):

Microstructure Evolution ◽

Superplastic Deformation ◽

Friction Stir Weld ◽

Friction Stir

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Deformation Behaviour of Accumulative Roll Bonded and Friction Stir Welded Aluminium Alloys

Materials Science Forum ◽

10.4028/www.scientific.net/msf.584-586.833 ◽

2008 ◽

Vol 584-586 ◽

pp. 833-839 ◽

Cited By ~ 3

Author(s):

Irena Topic ◽

Heinz Werner Höppel ◽

Matthias Göken

Keyword(s):

Friction Stir Welding ◽

Deformation Behaviour ◽

Friction Stir ◽

Ultrafine Grained ◽

Purity Aluminium ◽

Initiation And Propagation ◽

Hydraulic Bulge ◽

Commercial Purity Aluminium ◽

Von Mises ◽

Ultrafine Grained Microstructure

Commercial purity aluminium AA1050 and aluminium alloy AA6016 were accumulative roll bonded and subsequently friction stir welded. The microstructure of the conventional and ultrafine-grained materials produced by accumulative roll bonding is strongly affected by friction stir welding. The elongated ultrafine-grained microstructure of roll bonded sheets becomes coarser and equiaxed in the nugget region. Hydraulic bulge tests showed that higher burst pressure can be achieved for samples without friction stir welding than for the ones with friction stir welding. Localised deformation, crack initiation and propagation, as well as the final fracture occurred within the nugget. Friction stir welded AA1050 sheet showed similar achievable burst pressures and von Mises equivalent strains compared to the as-received conventionally grained sheets. On the other hand, significantly higher burst pressures and at the same time higher von Mises equivalent strains were observed for the friction stir welded ultrafine-grained material than for the friction stir welded conventionally grained material.

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