The effects of solution and aging treatments on the microstructures and mechanical properties of tungsten inert gas arc welded AZ61 magne-sium alloy joints were investigated by microstructural observations,microhardness tests and tensile tests.The results showed that the solution treatment led to the β-Mg17Al12 particles dissolved into the α-Mg grains.Hence,the microhardness of the fusion zone and the ultimate tensile strength of the welded joints were the lowest.With the increase of the aging temperature,the volume fraction of the β-Mg17Al12 particles in the fusion zone increased and this enhanced the microhardness of the fusion zone gradually.Also,the elongation of the welded joints was in-creased slightly with the increase of the volume fraction of the β-Mg17Al12 particles.However,the ultimate tensile strength of the welded joints increased at first and dropped at 190 ?C due to cracks formed at the boundaries of the β-Mg17Al12 particles.
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