Microstructural and mechanical inhomogeneity of laser beam (LBW) and friction stir (FSW) welded joints of 4 mm thick 6082-T6 Al-Mg-Si alloy was studied. Thermal cycles measured in heat affected zone (HAZ) showed that LBW has a much higher heating and cooling rates than FSW. Distribution of local microhardness and local strain in tensile specimens revealed that fracture of the joints corresponds to a region with minimum hardness. LBW tensile samples were fractured in weld metal, FSW samples - in HAZ. It has been found that tensile properties and ductility of joints is significantly lower than those of the base metal. The LBW and FSW joint efficiency in terms of yield stress was about 71% and 61% respectively. Joint efficiency in terms of elongation was 7.8% (LBW) and 19% (FSW). It is explained by the strain concentration in the lower strength joint region.Keywords: Friction stir welding, laser welding, Al-Mg-Si alloy, temperature field, microstructure
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