搅拌头尺寸对搅拌摩擦焊补焊的影响

Effect of the Stir Tool Size on Friction Stir Repair Welding

分别采用8.5 mm长小搅拌头和24 mm长大搅拌头补焊具有表面沟槽缺陷的42 mm厚的Al-Mg-Si合金FSW试板。试验结果表明,搅拌摩擦焊补焊工艺能够修复具有表面沟槽缺陷的FSW试板。两种搅拌头补焊的焊接接头焊核区晶粒比较细小。大搅拌头补焊焊道与原焊道的重叠区硬度下降明显,对接头的硬度影响范围比小搅拌头补焊时的大。拉伸结果显示,小搅拌头补焊接头抗拉强度比大搅拌针补焊的高16 MPa,屈服强度比大搅拌头的高6 MPa。大搅拌头补焊时带来的热输入高且影响范围大,会造成焊接接头力学性能下降,所以在满足消除缺陷的前提下,尽量选择短小的搅拌头进行补焊。

The 42 mm thick FSW plate of Al-Mg-Si alloy with surface groove defects was repair welded by 8.5 mm long small stir tool and 24 mm long large stir tool respectively.The test results show that the friction stir repair welding process can repair FSW joints with surface groove defects.The grains in the weld nugget zone of the welded joints welded by the two stir tools are small.The hardness of the overlapping area between the repairing bead welded by the large stir tool and the original weld bead decreases significantly,and the impact area on the hardness of the joint welded by large stir tool is larger than that welded by small stir tool.The tensile results show that the tensile strength of the welded joint welded by small stir tool is 16 MPa higher than that welded by the large stir tool and the yield strength is 6 MPa higher than that welded by the large stir tool.The large heat input and large influence range which caused by the welding of the large stir tool cause the decline of mechanical properties of the welded joint.Therefore,under the premise of satisfying defect elimination,small stir tool should be selected.