Effect of welding parameters on mechanical and microstructural properties of AA6056 joints produced by friction stir welding

The effect of processing parameters on mechanical and microstructural properties of AA6056 joints produced by Friction Stir Welding was analysed in the present study. Different samples obtained by employing rotating speeds of 500, 800 and 1000 rpm and welding speeds of 40, 56 and 80 mm/min were produced. The mechanical properties of the joints were evaluated by means of microhardness (HV) and tensile tests at room temperature. Fatigue tests on the welds were carried out by using a resonant electro-mechanical testing machine under constant loading control up to 250 Hz sine wave loading. The low cycle (LCF) and high cycle (HCF) fatigue tests were conducted in the axial total stress-amplitude control mode with R = σmin/σmax = 0.1, for all the welding and rotating speeds used in the present study. It was observed that the specimens welded at 56 mm/min showed the best behaviour in the low cycle regime. The microstructural evolution of the material was analysed by optical observations of the welds cross sections.