2024-T3铝合金搅拌摩擦连接接头力学性能研究

Study of Joint's Mechanical Properties of Friction Stir Welding of 2024-T3 Aluminum Alloy

以搅拌头旋转速度和连接速度为变量,设计了9组不同的连接参数,对3mm厚2024-T3铝合金进行搅拌摩擦连接试验,采用拉伸试验和小孔切割应力释放法测量了连接接头的抗拉强度和上下表面纵向残余应力。结果表明,接头上表面纵向残余应力均呈"M"型分布,下表面均呈倒"V"型分布;随着搅拌头旋转速度和连接速度的增大,接头的抗拉强度及延伸率先增大后减小,上表面前进侧、后退侧和下表面的纵向残余应力峰值先减小后增大;搅拌头旋转速度对接头抗拉强度及纵向残余应力峰值的影响要比连接速度大;当搅拌头旋转速度1 050 r/min,连接速度200 mm/min时,接头的抗拉强度最大,达到母材强度的81.2%,接头上表面前进侧、后退侧和下表面的纵向残余应力峰值最低。

Taking the stir-welding head spinning velocity and joining speed as the variables, 9 sets of stir-welding joining parameters are set up for the 3mm thickness of 2024-T3 aluminum alloys to give its friction stir welding joining test. The tensile tests and small hole cutting stress-release method are adopted in the measurement of the stress of extension and joining head and vertical residual stress of the top and the bottom surfaces. The result shows that the ＇ M＇ shape distribution appears in the vertical residual stress of the top surface and the ＇ V＇ shape distribution appears in the bottom surface. With the increase of the stir-welding head spinning velocity and joining speed, the extension stiffness and ductility of the joint are the first to increase and the last to decrease, and the peak value of the vertica residual stress is the first to decrease and the last to increase in the leading s{de and backing side of the upper and bottom surfaces. When the stir-welding head spinning speed is up to 1050 r/min and the joining speed is up to 200mm/min, the extension stiffness is maximal, when its value is up to 81.2% of the base material, and the vertical residual stress in the leading side and backing side of the upper and bottom surfaces is at minimal.