高功率激光深熔焊接孔内气流与孔壁的耦合行为研究

Study on Coupling Behavior of Keyhole Flow and Keyhole Wall in Deep Penetration Laser Welding

摘要: 激光深熔焊接过程中深熔小孔内金属蒸气与焊接熔池孔壁之间存在直接相互作用的气液流体动力学耦合行为，决定着焊接稳定性并影响最终的焊接质量。本文将不锈钢金属板材与玻璃组合夹紧制成异种材料对接接头，实现异种材料的激光深熔焊接。采用高速相机从玻璃一侧对小孔形态和孔壁波动特征进行观察研究，分析了不同焊接条件下蒸气与孔壁的相互力学耦合作用及其产生的规律。结果显示孔内蒸气流的作用促使小孔壁形成移动波，移动波在小孔开口处破碎时伴随着飞溅和液柱的形成。低速焊接时，小孔深、孔内蒸气波动大，后沿孔壁波动频繁。激光束离焦量的变化，使得小孔直径和孔内激光能量分布发生变化，导致孔内蒸气流的压力和流速发生变化，从而改变了孔内金属蒸气对孔壁的作用大小。熔透激光深熔焊接时，在气化反冲压力和蒸气流的驱动下，后沿孔壁上的液态金属主要为向上流，只有接近孔底的小部分金属熔液向下流。

Abstract: The hydrodynamic coupling behavior of gas-liquid interaction between the metal vapor in the keyhole and the keyhole wall during deep penetration laser welding determines the welding sta-bility and affects the final welding quality. In this paper, stainless steel sheet metal and glass were clamped to make a dissimilar materials butt joint, and then the deep penetration laser welding of dissimilar materials was achieved. A high-speed camera was used to observe the characteristics of keyhole and the fluctuation of the keyhole wall from the glass side. The interaction behaviors between the vapor and the keyhole wall under different welding conditions were analyzed. The results showed that the effect of the vapor flow in the keyhole caused the keyhole wall to form a moving wave, which was accompanied by the formation of splash and liquid column when the moving wave crushed at the opening of the keyhole. During low speed welding process, the keyhole was deep, the keyhole vapor was fluctuating, and the keyhole wall was fluctuating frequently. The variation of laser beam defocusing distance effected the keyhole diameter and the laser energy distribution in the keyhole, and resulted in the change of the pressure and velocity of the vapor flow in the keyhole, thus changed the effect of the metal vapor on the hole wall in the keyhole. In deep penetration laser welding, the liquid metal on the rear keyhole wall was mainly moving upwards, which was driven by the gasification recoil pressure and vapor flow, and only a small part of the molten metal closing to the bottom of the keyhole was moving downwards.

文章引用：李时春, 许伟, 廖生慧, 陈根余. 高功率激光深熔焊接孔内气流与孔壁的耦合行为研究[J]. 应用物理, 2017, 7(11): 304-312. https://doi.org/10.12677/APP.2017.711038

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