Reduction of hot cracking susceptibility during laser welding of aluminum by vibrations

Abstract

Hot cracking is one of the main issues in welding of 6xxx aluminum alloys. Aim of this study is to identify the influence of applied vibrations on the hot cracking susceptibility during laser welding. Close-edge welding of EN AW-6082 sheets with and without vibrations was carried out. The total length of the centerline hot cracks and the resulting grain structure of the welds were determined. The silicon and magnesium element distributions were quantified by wavelength dispersive X-ray spectroscopy. The presence of low melting phases close to the centerline was analyzed by differential scanning calorimetry. The results show that the total length of hot cracks was significantly reduced by the applied vibration while the grain size and structure were not affected in the case of the used excitation conditions at a welding velocity of 6 m/min, whereas no significant influence was observed at lower welding velocities. The weld seams do not show an enrichment of silicon and magnesium close to the center line—macrosegregations—or an influence of the excitation on their distributions. The study shows that the avoidance of low melting phase compositions in the seam center is an influencing factor regarding the reduction of the hot cracking susceptibility by vibrations.