Mechanical properties of cold rolled friction stir welded sheets in AA5754 aluminium alloy

The effect of cold rolling on the mechanical properties and formability of friction stir welded sheets in AA5754-H114 aluminium alloy was studied. To this end, friction stir welding (FSW) was carried out on 2.5 mm thick sheets with constant values of rotational and welding speeds of 1200 rpm and 100 mm/min, respectively. Part of the FSWed blanks was cold rolled, with the rolling direction perpendicular to the welding line, until reaching a uniform and constant sheet thickness of 2.4 mm. In order to investigate the influence of the friction stir welding on the final properties of the blanks, cold rolling was also carried out on strips in the as-received condition. Finally, mechanical properties and formability of base material and friction stir welded joints, before and after cold rolling, were evaluated by means of uniaxial tensile and hemispherical punch tests; the nominal stress vs. nominal strain and punch force vs. punch stroke curves were analyzed in detail.