Development of multivortex flow of a stainless-steel melt under the action of laser radiation on its surface

A numerical investigation was made of the structure of thermocapillary convection of a laser melt formed by radiation with various parameters in the specific case of SS304 stainless steel. A critical Reynolds number was found: above this number a single-vortex structure of the melt flow changed to two vortices. A comparison of the shape of the molten pool predicted by numerical calculations with experiments confirmed the existence of a two-vortex structure initiated solely by thermocapillary forces on the melt surface. A correlative dependence was proposed for relating the laser radiation parameters to those of the molten pool when a two-vortex flow structure appeared.