旋转速度对镁/铜异种金属搅拌摩擦焊接头成形及拉伸性能的影响

Effect of Rotation Speed on Formation Quality and Tensile Properties of Friction Stir Welding Dissimilar of Mg/Cu Alloys Joints

保持95 mm/min焊接速度不变的条件下,通过改变旋转速度研究其对镁/铜异种金属搅拌摩擦焊接头成形和力学性能的影响。结果表明:采用750 r/min搅拌头旋转速度焊接时,焊缝表面出现起皮现象;焊核区底部形成明显的隧道槽缺陷。适当增加搅拌头旋转速度至950 r/min时,焊缝表面变得更光滑;混合区尺寸增大;内部隧道槽缺陷消失;该混合区主要由被搅碎的Mg、Cu合金和少量新生成的Mg2Cu金属间化合物组成;接头的抗拉性能最好,抗拉强度达81.7 MPa;但是,继续增大搅拌头旋转速度至1180 r/min时,不利于接头成形,混合区底部有细小的孔洞缺陷产生。

In this work,maintaining the welding speed at 95 mm/min,effect of rotation speed on formation quality and tensile properties of friction stir welding dissimilar of Mg/Cu alloys joints was studied.The results show that,there are some flash on the weld surface and obvious tunnel channel defect on the bottom of the weld nugget zone when a low rotation speed of 750 r/min is applied.With increasing rotation speed to 950 r/min,the weld becomes smoother,the size of the weld mixed zone enlarges and the tunnel channel defect in the weld mixed zone disappears.The micro-structure of the weld mixed zone is comprised of broken copper-magnesium alloys and a small amount of Mg2Cu intermetallic compound.Moreover,the tensile performance of the joint is the best with the average tensile strength high up to 81.7 MPa.However,continuously increasing the rotation speed to 1180 r/min,some small holes form on the bottom of the weld mixed zone,which is not conducive to the joint formation.