半螺纹搅拌针对2024铝合金搅拌摩擦搭接焊力学性能影响

作为影响搅拌摩擦焊（FSW）过程中塑性材料上下流动的重要因素，搅拌针螺纹形貌同样对搅拌摩擦搭接焊（FSLW）的材料流动和力学性能有着重要影响.为研究半螺纹搅拌针对FSLW接头显微组织和力学性能的影响，文中将全螺纹搅拌针和半螺纹搅拌针用于包铝2024铝合金FSLW试验，并对不同搅拌针作用下的FSLW接头的横截面形貌、剪切拉伸载荷、断裂位置等方面进行分析对比.结果表明，半螺纹搅拌针会使钩状缺陷向下弯曲，从而使FSLW接头具有较大的有效板材厚度以及搭接宽度.断裂模式同为剪切断裂，但半螺纹搅拌针作用下的FSLW接头拥有更大的拉断载荷.

Effect of half-threaded pin on mechanical properties of friction stir lap welded alclad 2024 aluminum alloy

As the main reason for the vertical flow of the plastic material during FSW, pin thread geometry plays an important role on material flow and mechanical properties of friction stir overlap welded(FSLW) joints. In order to investigate the effect of the half-threaded pin on the microstructure and mechanical properties of FSLW process, the full-threaded pin and the half threaded pin were used to welded alclad 2024 aluminum alloy, respectively. Cross-section of the joint, lap shear failure load, fracture position were studied. Results show that the half-threaded pin easily causes the hook to bend downwards, leads to the bigger effective sheet thickness and lap width. The fracture mode is shear fracture, and FSLW joint with the half-threaded pin owns the higher shear failure load.