Experimental Observation of Hydrodynamics of Melt Layer and Striation Generation during Laser Cutting of Steel

We investigated striation generation mechanism in inert gas laser cutting of steel by experimental observations of hydrodynamics of melt layer on the kerf front. It was found that the melt flows in the regions of kerf side and kerf front exhibit instability in different velocity ranges. This new evidence, which has not been discussed in the past, is essential, because it is the instability in the side region that causes periodical initiation of the striations from the surface. We also discuss the origin of the instability using a simple physical model