Internal Material Flow Layers in AA6082-T6 Butt-Joints during Bobbin Friction Stir Welding

被引:14
作者
Tamadon, Abbas [1 ]
Pons, Dirk J. [1 ]
Clucas, Don [1 ]
Sued, Kamil [2 ]
机构
[1] Univ Canterbury, Dept Mech Engn, Christchurch 8140, New Zealand
[2] Univ Teknikal Malaysia Melaka, Fak Kejuruteraan Pembuatan, Durian Tunggal 76100, Malaysia
关键词
bobbin friction stir welding; materials flow; metallography; AA6082-T6; weld defect; MECHANICAL-PROPERTIES; ALUMINUM; TOOL; MICROSTRUCTURE;
D O I
10.3390/met9101059
中图分类号
T [工业技术];
学科分类号
08 ;
摘要
Bobbin friction stir welding with a double-sided tool configuration produces a symmetrical solid-state joint. However, control of the process parameters to achieve defect-free welds is difficult. The internal flow features of the AA6082-T6 butt-joints in bobbin friction stir welding were evaluated using a set of developed reagents and optical microscopy. The key findings are that the dark curved patterns (conventionally called 'flow-arms'), are actually oxidation layers at the advancing side, and at the retreating side are elongated grains with a high-density of accumulation of sub-grain boundaries due to dynamic recrystallization. A model of discontinuous flow within the weld is proposed, based on the microscopic observations. It is inferred that the internal flow is characterized by packets of material ('flow patches') being transported around the pin. At the retreating side they experience high localized shearing at their mutual boundaries, as evidenced in high density of sub-grain boundaries. Flow patches at the advancing side are stacked on each other and exposed to oxidization.
引用
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页数:22
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