铝合金型材间隙填料搅拌摩擦焊接头疲劳性能研究OA

To address the joint formation and service performance issues caused by assembly gaps during friction stir weld-ing(FSW)of 6005A-T6 aluminum alloy extruded profiles for rail vehicles,FSW joints with a 1 mm gap were fabricated us-ing two gap-filling methods:6005A aluminum alloy homogeneous filler strip(1 mm thick)and ER5087 aluminum alloy het-erogeneous filler wire(1 mm in diameter).The joints were produced under optimized welding parameters(rotational speed of 800 rpm and travel speed of 200 mm/min),and the effects of the two filler methods on high-cycle fatigue performance and fracture behavior were comparatively investigated.The S-N curve results indicate that the fatigue strength at 10⁷ cycles of the homogeneous filler-strip joint is approximately 40 MPa,while that of the heterogeneous filler-wire joint increases to approximately 70 MPa,representing a significant improvement in fatigue performance.Fatigue fracture in both types of joints predominantly occurs in the heat-affected zone(HAZ)and parent material(PM),rather than in the stir zone(SZ).No crack propagation along the"S-line"or hook defects is observed,indicating that under the optimized parameters,the intro-duced filler materials are not the dominant factor controlling fatigue failure.Fractographic analysis reveals that fatigue cracks generally initiate from the specimen surface corners or beneath the welding ripples,the crack propagation region ex-hibits predominantly cleavage characteristics,and the final fracture region displays dimple morphology.These results pro-vide experimental references for the selection of gap-filling FSW process schemes for aluminum alloy profiles in rail vehicle applications.