Keyhole behavior and pressure distribution during laser irradiation on molten metal Available to Purchase

In order to profoundly understand laser keyhole -type welding phenomena, a YAG laser beam was irradiated on a molten metal of Zn. This corresponds to the conditions under which the effect of a solid wall in general laser welding is eliminated. During laser irradiation, keyhole evolution was observed by X-ray transmission method. It was consequently revealed that bubbles were predominantly generated from the tip of a keyhole, which is the same formation mechanism as we revealed in general laser welding at low speeds. Furthermore, pressure distribution in a keyhole was calculated from the keyhole shapes considering the curvature and the depth measured from the observed X-ray images. The pressure was evaluated in comparison with a value measured experimentally by an electric balance. Both results showed that the pressure of a keyhole was approximately 5 kPa near the bottom. It was also confirmed that bubbles were never generated from a stable rice-bowl-shaped keyhole whose pressure decreased gradually from the bottom toward the surface.