Bead-on-plate welding of pure copper with a 1.5-kW high-power blue diode laser

The authors developed a 1.5-kW blue diode laser system, and the keyhole-mode welding behavior was observed during bead-on-plate welding of a pure copper plate. Pure copper is widely used for various industrial products due to its outstanding high thermal conductivity, electrical conductivity, and friction properties. However, high-quality and high-efficiency connections of copper materials remain a challenge for industrial applications because pure copper has a low absorption rate of near-infrared light and is difficult to weld stably with a near-infrared laser. A blue laser, which has a light absorption rate about six times higher than that of near-infrared light, may be advantageous for pure copper welding. Herein, a 1.5-kW blue diode laser system exhibits a keyhole-mode welding behavior during bead-on-plate welding of a 2-mm-thick pure copper plate. The heat input efficiency is calculated, and the effects of the output power and scanning speed on welding efficiency are investigated. The melting efficiency is about 1% during thermal conduction-type welding, but increases about five-times when transitioning to keyhole-mode welding. At an output power of 1450 W and a scanning speed of 100 mm/s, spatter-free keyhole-mode welding is achieved with a blue diode laser.