不同装配条件下6005A-T6铝合金型材焊接接头疲劳性能

Fatigue properties of 6005A-T6 aluminum alloy joints under different assembly conditions

针对装配错边量参数如何影响搅拌摩擦焊接头的焊接质量和疲劳强度的问题,采用高速列车用6005A-T6铝合金作为母材,使用双轴肩对接方法制备了各种对接参数的BT-FSW接头,同时对各组疲劳断口进行了SEM分析。结果表明:随错边量的增加,接头指定1×10^(7)循环次数疲劳强度明显降低;当错边量控制在0.5 mm以内时,焊接接头的疲劳强度水平较高,在指定疲劳寿命下拥有更高的疲劳强度而不开裂;装配错边量超过0.8 mm时,疲劳强度迅速下降,且疲劳试件断裂位置多萌生于焊核边缘。SEM结果显示:启裂区疲劳源清晰,具有典型的疲劳断裂特征;扩展区疲劳纹与裂纹延伸方向垂直;终断区可观察到典型的纯韧窝状韧性断口。

Aiming at the problem of how the assembly error parameters affect the welding quality and fatigue strength of friction stir welded joints, the 6005 A-T6 aluminum alloy butt-joints of bobbin tools friction stir welding, which design for high-speed train were studied respectively through scanning analysis for the fatigue fractures. The results showed that the limit strength of joints median value fatigue that specifies life of 1×10^(7) decreased with the increase of misalignment obviously, it had higher fatigue ultimate strength without cracking under specified fatigue life when the amount of misalignment was controlled within 0.5 mm, when the amount of misalignment exceeded 0.8 mm, the fatigue strength decreased rapidly and the fracture position of the specimen in the fatigue test was mainly located in the weld nugget edge area. The scanning image showed that the panorama of the fracture was like fibrous with clear source of fatigue, which had typical fatigue fracture characteristics, the fatigue beach of the crack extending zone was vivid perpendicular to the extending direction, a typical deep dimple-like tough fracture could be observed in the termination zone.