| Friction stir welding has many advantages such as good joint quality, low residual stress and distortion, and high fatigue strength, so it has been used in the manufacturing of aeronautics, astronautics, shipbuilding and vehicle. But, to heat treatment strengthening type aluminum alloy, over-aging still is a severe problem up to now and welding processing optimization has still not evident effect to the improvement of load bearing ability.In this paper, the heterogeneous deformation behavior and mechanism of friction stir welding joint of6061-T6Aluminum alloy by digital image correlation. The finite element simulation of mechanical response of joint was conducted under tensile load. The influence of joint geometry on the stress and strain was analyzed. Science foundation was established for the optimization of friction stir welding processing and the improvement of the load bearing ability of joint.The position and geometry of micro-zone of friction stir welding joint can be correctly identified by the combination of traditional micro hardness measurement and strain measurement of advanced digital image correlation. Based on iso-stress condition and the full stain results, the local mechanical properties and stress-train relation can be obtained. The finite element simulation of mechanical behavior of friction stir welding joint of6061-T6Aluminum alloy was realized under tensile load. The results of the simulation and experiment have good similarity.The influence of the geometry variation of local micro-zone of friction stir welding joint on mechanical response under tensile load was studied by finite element simulation. With the decreased the sizes of heat affect zone, thermally-mechanical zone, and welding nugget, the constraint of the base material is increased, the stress and strain of the heat affect zone, thermally-mechanical zone, and welding nugget are decreased. As a result, the load bearing ability of friction stir welding is improved. |
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