Seam Formation in Laser Beam Micro-Welding with Spatial Power Modulation

Abstract

When laser sources of high brilliance are used for the micro-welding of metals, small seam dimensions are generated. If the spatial power is modulated by a superposition of the linear feed rate and a circular-oscillatory movement of high frequency, the width of the seam is controlled by the amplitude of the circular movement. In this study, the irradiation pattern of the seam was calculated and reveals that some spots of the seam area are not irradiated, while other have been irradiated several times. The seam shapes were visualized with micro cross-sections for different laser powers, linear feed rates and oscillatory amplitudes. Thermal simulations were made to discuss the different seam shapes. A consequence of the oscillatory movement is the appearance of different solidification fronts, which are visible in the micro cross-sections.