High-speed single-pulse welding with Nd:YAG lasers (Invited Paper)

High speed contour weldings with feed rates in the range of meter per second are performed by single pulses of Nd:YAG lasers with real time pulse control.The pulse length may be up to 100ms leading to a possible contour length of more than 100mm. The properties of the weld pool was investigated with direct beam and a beam delivered via fiber on the metallic workpiece. Micrographic pictures show, that with fiber the profile (depth and shape) of the melted zone is quite constant along the contour, while for the direct beam the profile is strongly influenced by the change of thermal lensing of the laser rod during the pulse. Corrections are possible by applying temporal pulse forming. The effect of this highly dynamic welding strategy on the joining of similar and dissimilar metals, which show quality problems in conventional seam welding, is investigated. The results demonstrate an improvement in the metallurgy (e.g. cracks), mechanical and visual properties in most joining tasks.The advantages and limits of this micro-welding strategy will be discussed.