Microstructure And Mechanical Properties Of 6082-T6 Thick Aluminum Alloy Joints Welded By FSW

Today, Motor car industry, such as high speed rail, subway, light rail, etc.has been national attention and support. Passenger car body weight severely limits the speed of passenger space, so to reduce weight on the passenger car industry is of paramount importance. Selected light metal such as high strength aluminum alloy can greatly reduce the weight of passenger cars, But like the traditional aluminum welding heat input makes the welded joints excessive performance degradation, Molten aluminum alloy are also prone to defects, serious impact on traffic safety. This paper introduces a new concept: Friction stir welding, This kind of welding method and the traditional welding methods biggest difference is the temperature below the metal melting temperature solder, Plastic flow of metal materials only to the temperature to complete the welding. Aluminum not only reduces the risk of weld defects, and effectively ensure the weld quality.6082 aluminum alloy is heat strengthened, with moderate strength and good corrosion resistance and welding properties is the main material of China's high-speed train body. Friction stir welded joint compared with the MIG welded joint, welded joint strength; the welding process does not produce welding defects such as cracks, holes and burning of alloying elements; Without filler material and shielding gas, Before welding without need for complex Pretreatment, welding residual stress and distortion; No welding arc radiation, dust and splash, low noise; Energy consumption of traditional welding methods only about 20%. Therefore, the manufacture of high-speed trains currently using friction stir welding technology has become mainstream.In this paper, the authors investigated 30mm thick 6082-T6 aluminum alloy single-sided and double-sided FSW welded joints and mechanical properties. And were analyzed by single and double-sided FSW slicing thickness of the weld on the microstructure and mechanical properties. To further enhance the alloy FSW weld strength and the practical application of FSW to provide strong theoretical basis.FSW laboratory in the United States, on the thickness of 30mm,6082-T6 aluminum alloy single-sided access welding, weld microstructure of two samples can clearly distinguish the advancing side and retreating side, the advancing side heat affected zone and the base metal has significantly boundaries, The retreating side are no obvious boundaries. Advancing side appear more onion rings appearance, And the hardness of the lowest points in the heat affected zone advancing side. Tensile strength of single welded joints is 193.81MPa,60% of parent metal; Tensile strength of Double welded joints is 199.3 MPa, about 62.3% for the parent metal. Visible, Double-sided welding is better than single-sided performance. Hardness of the two welded joints appear the same rules,Base metal higher-the heat affected zone advancing side down low heat affected zone has increased-the highest nugget zone (below the base metal) retreating side heat affected zone fall-the heat affected zone fell to the lowest point base metal has increased.changes in hardness between various zones have a certain range. The hardness of weld nugget zone 65HV-70HV; heat affected zone is relatively low hardness of 55HV-60HV.