It was studied the effect of the welding procedure on the temporal evolution of the mechanical properties in AA 7075-T651 friction stir welded joints. To vary the heat input samples with different parameters (rotation and welding speed) were welded. Thermal cycles were acquired by means of thermocouples instrumented on the samples, obtaining the heat input for each case. The welded joints were macrostructural characterized using optical microscopy. Vickers microhardness profiles and tensile tests were measured for different times after welding (between 1and 900 days).The minimum hardness (HVmin) value was located in the heat affected zone (HAZ). That HVmin decreased with heat input and was increased with the time elapsed after welding showing a logarithmic relationship, for the different welding conditions analyzed. This HVmin increasing was higher for the sample welded with the lower heat input. Tensile strength of welded joints increased with the time after welding, according to a logarithmic relation too, reaching an joint efficiency of 80%.
FSW; aluminum; AA 7075-T651; strain aging; mechanical properties
