旋转速度对铝合金搅拌摩擦焊接头弯曲性能的影响

Influence of rotational speed on bending property of aluminum alloy friction stir welded joints

对2219-T6铝合金进行搅拌摩擦焊接(FSW),并采用三点弯曲试验方法评价接头的弯曲性能和用扫描电镜观察接头的弯曲断口形貌。结果表明:正弯时拉应力作用于FSW焊缝上表面,压应力作用于下表面,表现出较好的塑性变形;背弯时受力相反,下表面中心线出现裂纹并沿焊核区与热机影响区之间的过渡区扩展。无缺陷FSW接头的最大弯曲力Fbb和抗弯强度σbb最大值分别为3.6 k N、503 MPa,以韧性断裂方式为主;而有缺陷FSW接头的Fbb和σbb分别仅为2.5 k N、395 MPa,以准解理断裂方式为主。

2219-T6 aluminum alloy was friction stir welded to investigate the ability of bending properties. That was evaluated by means of three-point bending test,and the fracture surfaces of the bend specimens were characterized using SEM to understand the failure patterns. The results indicate that the top surface of weld subjects to tensile stress and the compressive stress is acted on the bottom surface during the face-bend test. The ability of bending plastic deformation is better without crack. The stress condition is contrary to the face-bend test as the root bend test,and the weld centerline of bottom surface appears microcrack and extends along boundary between the weld nugget zone and thermo-mechanical zone. The maximal bending force and strength reaches 3.6 kN, 503 MPa in flaw-free weht and most of failure is the result of ductile fracture. The joint with flaw is only to 2.5 kN, 395 MPa and mostly by means of quasi-cleavage fracture, respectively.