CR400BF型高速动车组双轴肩搅拌摩擦焊部件质量提升

Quality improvement of bobbin friction stir welding parts of CR400BF high-speed train

采用双轴肩搅拌摩擦焊工艺对中国标准化动车组铝合金车体前端底板进行焊接。在前端底板生产中,焊接一次合格率(相控阵超声检测)低于50%,严重影响焊接质量及交车进度。针对上述问题对焊接缺陷进行研究,使用ABAQUS模拟孔洞型缺陷的形成机理,发现在合适的工艺参数下可以避免孔洞型缺陷的产生。采用光学显微镜(OM)和扫描电子显微镜(SEM)对正常断裂和异常断裂的"之"形线进行研究,探讨了两类断裂中"之"形线的来源以及形成机理。通过将原有"三棱锥"形状的搅拌针改为"正反双螺旋"形状的搅拌针,并系统改进焊接工艺,焊接一次合格率达到了100%。

Some parts of aluminum alloy body of China Standardized EMU are welded by friction stir welding. The front bottom plate adopts bobbin friction stir welding process. During the production of the front bottom plate, the first pass rate of welding(phased array ultrasonic testing) is less than 50%, in view of the strict requirement on quality, it seriously affects the welding quality and delivery schedule. Aiming at the above problems, the welding defects were studied. ABAQUS was used to simulate the formation mechanism of cavity defects, cavity defects can be avoided with appropriate parameters. The normal and abnormal fracture zigzag lines were studied by OM and SEM, the origin and formation mechanism of the zigzage lines in the two kinds of defects were discussed. Through the improvement of the tool profile, the original triangular prism shaped agitator needle is changed into a positive and negative double helix shaped agitator needle, the research of welding technology has been improved systematically, the first pass rate of welding reaches 100%.