Characteristics of Microstructure and Hardness in Friction Stir Welded 7075 Aluminum alloy Joints(Materials, Metallurgy & Weldability)
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The present study focuses on the characteristics of microstructure in the joint region of A 7075 aluminum alloy. A 7075 aluminum alloy plate with a thickness of 5mm was prepared for the joining. The FSW was performed for butt joints of the alloy with a welding speed and rotating ratio of 300mm/min. and 1500rpm, respectively. Microstructures of the joint region were investigated utilizing the OM, SEM and Electron Back-Scatter Pattern (EBSP) methods. Hardness of the joint was measured by the Vickers micro-indentation system. Grain refinement was achieved in the stirred zone of the joint, but the lowest hardness was obtained in this region. Each grain belonging to the same orientation group tended to form "clusters", and some clusters seemed to be lying along the plastic flow caused by the rotation of the pin. Spatial distributions of microstructure parameters were identical, depending on the area in the joint region observed. In other words, we have obtained an advanced technique for microstructure control that enables us to fabricate peculiar microstructures in limited regions by utilizing FSW or friction stirring in the surface region.
- Transactions of JWRI
Transactions of JWRI 33 (1), 17-23, 2004-09