Local Mechanical Properties Estimation of Friction Stir Welded Al-Mg-Si Joints

摘要

Dramatic change of properties happens due to diffusion processes inmetal during friction stir welding. The information on influence offriction stir welding thermo mechanical cycle on local mechanicalproperties of thermo hardenable Al-Mg-Si alloy joints is limited.Purpose of this work is investigation of local mechanical properties andmicrostructure of FSW Al-Mg-Si joints.Microstructure and mechanical properties of friction stir welded jointsof 4 mm thick 6082-T6 Al-Mg-Si alloy were studied. Welded jointshave a distinct heterogeneity of microstructure and mechanicalproperties. The asymmetry of peak temperature field andmicrohardness distribution in heat affected zone was revealed. Thewelded joints efficiency in terms of yield stress was about 72%.Elongation of welded joints is 5.3 times lower than base metal due tostrain concentration in the zone of minimum hardness. The prolongeddwell time at high-temperature leads to a significant decrease of thehardness in the metal of heat affected zone which is probably caused bythe dissolution of the hardening particles. The dependence betweenyield strength and hardness of 6082 alloy is obtained which can be usedfor estimation of local joint mechanical properties.