Local formability improvement of 6111-T6 aluminum alloy sheet through high-speed robotic friction stir processing

Abstract

This study examines the impact of friction stir processing (FSP) on the local formability of 6111-T6 aluminum alloy sheets, utilizing sub-scale tensile and VDA bend tests, along with electron microscopy for microstructural analysis. Results show that FSP notably increased uniform and total elongation by 100% and 50%, respectively, though it reduced yield and ultimate tensile strength. Electron backscatter diffraction revealed significant deformation within shear bands and varied fracture paths: intergranular for FSP due to increased grain boundary density and a mix for T6. FSP’s grain refinement facilitated plastic deformation at crack tip leading to blunting and enhanced fracture toughness thus improved bend properties.