To solve the problem of direct observation of the keyhole during deep penetration welding, a modified "sandwich" specimen was proposed to directly observe the keyhole during deep penetration laser welding with a 10 kW fiber laser. A distinct keyhole wall and liquid motion along the wall were observed directly. The moving liquid "shelf" on the front keyhole wall and the accompanying hydrodynamic and vapor phenomena were observed simultaneously. Micro-droplets torn off the keyhole wall and the resultant bursts of vapor were also visualized. The emission spectrum inside the keyhole was captured accurately using a spectrometer to calculate the characteristics of the keyhole plasma plume. The experimental results suggest that the hydrodynamics on the keyhole wall has a dominant effect on the weld defects.%为了解决深熔焊接小孔难以直观观测的难题,提出改进的"三明治"方法,并对10 kW光纤激光深熔焊接小孔进行了直观观测,观测到激光深熔焊接清晰的小孔内壁及沿着孔壁的液体流动. 对小孔前沿壁上流动的液体"台阶"及其伴随的流体动力学和蒸汽现象进行了同步观测. 观测了金属微滴脱离小孔壁过程及所导致的蒸汽爆发现象. 采用光谱仪对小孔内部光谱信号进行了精确探测并计算了孔内光致等离子体特征参数. 试验结果表明:小孔壁的流体动力学行为对焊接缺陷的产生具有决定性影响.
展开▼
