MECHANICAL AND CORROSION BEHAVIOUR OF FRICTION STIR WELDED AA7075 T-651 ALUMINIUM ALLOY JOINTS
Keywords:Aluminium alloy, Friction stir welding, Fracture toughness , pitting corrosion
High strength heat treatable aluminium alloy AA7075T-651 is widely used in aircraft, defence and automobile industries. However, the application of aluminium alloy in marine environment exhibits poor corrosion performance. High strength aluminum alloys are very difficult to weld in fusion technique due to poor solidification and microstructure in nugget zone. Friction Stir Welding is reliable technique to join aluminium alloys in solid state condition with sound weldability. In this work, rolled aluminium plate with thickness of 10 mm were square butt welded by Friction Stir Welding (FSW) process. The corrosion behavior and mechanical properties of FSW joints were investigated comparatively and in detail. The microstructure changes of substrate metal and weld nugget zone of FSW was studied using optical microscope. The mechanical behaviors such as fracture toughness, tensile strength and hardness test have been carried out in substrate and weld metal. Pitting corrosion resistant was determined by potentiodynamic polarization test. It was observed that, the mechanical properties and corrosion resistant of weld joint is lower than the base metal.
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