搅拌头倾角对FSW成形和接头力学性能的影响

Effect of tool tilt angle on formation and mechanical property of FSW

研究了搅拌头倾角对FSW接头焊核区材料的塑性流动和接头力学性能的影响.结果表明,焊接速度一定,倾角θ小于1.5°时,在搅拌头轴肩下0.5 mm处出现隧道型缺陷,搅拌针下部的焊核金属发生沉积;随着倾角θ增大,焊核区的金属发生强烈地塑性变形和流动,缺陷逐渐消失,焊核区变宽.对焊接接头拉伸断口进行扫描电镜观察发现:当θ为2°时,在焊核区上表面位置出现'弱连接'现象.断口和力学性能综合分析表明,当θ为3.5°～4°时,焊核区宽度最大,LF5铝合金接头强度和延伸率分别达到最大值:305 MPa和16%.

The effect of the tool tilt angle on the characteristics of LF5 aluminum alloy by friction stir welding such as the material flow and mechanical property was introduced. Tunnel defect is observed at 0.5mm below the tool shoulder as the tilt angle θ is less than 1.5°. Material at lower portion of nugget is deposited. With the increase of θ, deformation and material flow of nugget become more serious, the nugget become wider and the defect disappears gradually .When θ is 2°, kissing bond was found in the upper region through the observation of fracture by SEM. If θ is between 3.5° and 4.5°, the nugget gains its largest width, the joint obtains the max tensile strength (350MPa) and toughness(16%).