Welding of aluminium and steel with high-power fibre lasers

Abstract

High-power fibre lasers for materials processing have undergone a rapid development process within the past two years. The modular structure of the systems has, in this short period of time, enabled the scaling of laser power from several hundreds of Watts to 10 Kilowatts and potentially even more. Due to its specific advantages, among which there are a beam quality significantly improved compared to other solid-state lasers, a high energetic efficiency and a compact size, they might well be considered to be a future alternative (in view of technical and economic aspects) to both Nd:YAG- as well as to CO2-Lasers. However, principle studies on its readiness for welding steel and aluminium alloys are still lacking.Thus, at the BIAS Bremer Institut fur angewandte Strahltechnik GmbH, a basic experimental programme on welding of various steel and aluminium materials with a fibre laser possessing a maximum beam power of 6.9 kW was performed. The central aim of the experiments was to explore the potentials of this new type of laser and demonstrate its ability to enhance the process limitations considering welding speed and sheet thickness previously regarded to be inevitable when welding with solid-state lasers.Compared to Nd:YAG-Lasers with a maximum beam power of 4 kW (nowadays a standard laser in industry), the penetration depth could be significantly increased. E.g., a penetration depth of up to 8 mm with a sufficiently narrow seam width could be achieved, and for sheets of 3 mm thickness, an increase of laser power from 4 to 7 kW nearly doubles the possible welding speed. For aluminium materials, very stable processes have been obtained even at a welding depth of more than 6 mm.In general, the results have been so promising for all materials tested that first studies on other industrially relevant joints such as overlap joints of zinc-coated steel or aluminium have been conducted.High-power fibre lasers for materials processing have undergone a rapid development process within the past two years. The modular structure of the systems has, in this short period of time, enabled the scaling of laser power from several hundreds of Watts to 10 Kilowatts and potentially even more. Due to its specific advantages, among which there are a beam quality significantly improved compared to other solid-state lasers, a high energetic efficiency and a compact size, they might well be considered to be a future alternative (in view of technical and economic aspects) to both Nd:YAG- as well as to CO2-Lasers. However, principle studies on its readiness for welding steel and aluminium alloys are still lacking.Thus, at the BIAS Bremer Institut fur angewandte Strahltechnik GmbH, a basic experimental programme on welding of various steel and aluminium materials with a fibre laser possessing a maximum beam power of 6.9 kW was performed. The central aim of the experiments was to explore the potentials of th...