Abstract
Article applies a model of welding with high-power laser beam. As a result of heating the material in the area of a laser beam creates a narrow and deep keyhole. Welding in such conditions favors the formation of pores in the weld. In the presented model takes into account double curvature of the keyhole. Surface tension acting on the convex and concave part of the liquid surface, accordingly seeks to opening and closing keyhole. Intense evaporation in the area of a laser beam causes appearance of recoil force whose value increases with the surface temperature of liquid steel. It was found the temperature limit, above which the recoil is greater than the force originating from the surface tension. In such welding conditions, keyhole is deeper. Presented two-dimensional model of the process take into account the dependence of thermophysical material properties and characteristics of the laser beam. It was found a little influence of the sulfur content on the weld pool shape. The keyhole formed during the welding becomes asymmetric. The rear part of the keyhole moves away from the front and faults appear on the solid-liquid border. As the keyhole becomes deeper faults are becoming more numerous.