Friction stir welding of AA6082-T6 assisted with a novel encapsulated alumina interlayer: surface morphology, tribology, and topographic analysis

This study demonstrates how encapsulated alumina interlayers provide a simple and cost-effective solution for enhancing the surface properties and wear resistance of friction stir-welded (FSWed) AA6082-T6. Alumina concentrations of 4-12 vol.% encapsulated in aluminum foil were applied at the interface of 12-mm-thick AA6082-T6 joints, using a constant tool rotational speed of 600 rpm and welding speed of 100 mm/min. Surface characterization included visual inspection, hardness testing, wear behavior analysis under varying loads, and topographical assessment using the Abbott-Firestone technique. The results showed that the 4 vol.% alumina joint reduced surface roughness by 18% compared to the unreinforced joint. Vickers hardness increased with increasing alumina content, with the 12 vol.% joint exceeding the base plate hardness by 12%. The 12 vol.% alumina joint also demonstrated significant wear improvements, with a 67.5% reduction in wear rate and a 38.5% decrease in wear track width under a 25 N load. The wear mechanisms transitioned from severe to mild with increasing alumina content. Debris analysis revealed a 74.7% reduction in the average debris size for the 12 vol.% joint. The Abbott-Firestone analysis showed that this joint had the most stable surface during wear, with minimal peak zone reduction and maximum exploitation zone expansion. These findings highlight the potential of alumina interlayers to improve the surface quality and wear resistance of FSWed AA6082-T6 joints.