Effect of Dynamic Recrystallization Mode on Texture Type for the Friction-Stir-Welded 6082-T6 Aluminum Alloy

Herein we investigated the evolution of grain morphology, boundary characterization, misorientation distribution and texture at the retreating side, the very center and the advancing side of the nugget zone during friction stir welding of 6082-T6 aluminum alloys. The experiment was conducted by applying electron backscattered diffraction (EBSD)technique and with the assistance of orientation analysis software. It can be observed that intragranular dislocations stacked and reorganized, and small-angle subgrains formed at the retreating side of nugget zone during the welding process, owing to hot plastic deformation. Part of these formed small-angle grain boundaries subsequently transformed into large-angle grain boundaries by rotating, thus leading to "continuous dynamic recrystallization" and refinement of the coarse grain of base metal. Meanwhile, there formed (111) [110] shear texture, and many deformation substructures near (111)[110]orientation grains. Due to the superiority of (001)[100] cubic orientation substructures with respect to dislocation density and dislocation configuration, they would become the nucleus of "discontinuous dynamic recrystallization" under the action of welding thermal cycle and grow into (001) [100] cubic oriented grains. The rotary extrusion of the shoulder made the grains in nugget zone rotate along ND direction, and in consequence, (001) [110]rotated cube texture formed at the very center of nugget zone, while at the advancing side, finally formed (111) [110] shear texture and cube texture (001) [100]. © 2019, Materials Review Magazine. All right reserved.