Friction Stir Welding of Rapidly Solidified 6082 Alloy: Microstructure and Mechanical Properties

Abstract

This study investigates the microstructure and mechanical properties of friction stir welded (FSW) joints produced from AA6082 alloy fabricated by rapid solidification and hot extrusion. The base material exhibited a homogeneous microstructure with a fine average grain size of ~1.3 µm, significantly lower than the 5.5 µm measured for the conventionally processed reference material. The most favorable joint properties were obtained at a tool rotational speed of 1000 rpm. Under these conditions, the welded joint showed strength comparable to the base material, reaching 206 MPa UTS and 151 MPa YS, although with reduced ductility. EBSD analysis revealed only minor microstructural changes after welding, with the grain size in the stir zone remaining nearly unchanged at approximately 1.5 µm. These results demonstrate that the fine-grained microstructure of the rapidly solidified AA6082 alloy is largely preserved during FSW and highlight its potential for solid-state joining applications.