Effect of Backplate Thermal Diffusivity on Mechanical Properties of Double Sided Friction Stir Welded Aluminum for Ship Structure

The effects of backplate thermal diffusivity on mechanical properties of friction stir welded (FSW) aluminum alloy 5083 joints were studied in the present work. Three variation of backplate material, marble-block, mild steel and aluminum which represent low, medium and high diffusivity respectively, were used in the welding processes. The results showed that the increase of backplate thermal diffusivity resulted the decrease of the welding temperature. Defect free weld was obtained if backplate material was mild steel, whereas the other backplate material, marble-block and aluminum were obtained defect welds. The highest tensile strength as well as microhardness were obtained in the mild steel backplate.