HYBRID TECHNOLOGY LASER BEAM - ARC WELDING

U. Dilthey(1), U. Reisgen(1), A. Wieschemann(1)

(1)ISF-Welding Institute, Aachen University, Germany

The process of Laser Beam Welding (LBW) is today a well established joining process in industrial applications. On the one hand this technique allows to generate deep and narrow welds with high speed and low heat input. But on the other hand it demands high investment costs, a precise preparation of the workpieces and for some materials the weldability is restricted. The characteristics of the Gas-Metal-Arc (GMA) welding process are opposed to those of the LBW process. Due to the low investment costs in combination with the advantages of the use of filler wire it is established as a very flexible joining process. The disadvantages are the limited welding depth and speed which go together with a high thermal load of the workpiece.
In hybrid welding a laser beam (CO2 or Nd:YAG) is combined in one processing zone (plasma and molten pool) with an arc process (TIG, plasma or GMA). As a result of former studies it has been pointed out, that by coupling the processes synergistic effects could be observed. The disadvantages of the single processes can be avoided.
Several basic effects of the hybrid process are already well known. The arc process increases the ability of gap bridging not only by its filler material but as well by the wider process zone. Its power determines the width of the weld. The laser process is related to the formation of a keyhole due to a laser induced plasma. This plasma reduces the ignition resistance of the arc. Therefore the arc itself shows greater stability. The power of the laser determines the welding depth. Further it is known, that synergistic process effects lead to an increase of the process efficiency.
However, the enhanced welding possibilities lead to a remarkable increase of weldability and welding security of materials and construction. By the choice of process parameters and the adjusting of the working head's geometrical set-up the weld properties like geometry and metallurgical structure can be strongly influenced. Technically and economically interesting perspectives are thereby opened for future applications.
The capabilities of Laser Beam - Arc Welding Hybrid Processes for joining low and high alloyed steels and aluminum alloys in ship building, metal constructions and car body production will be presented.

Keywords: GMA, CO2-Laser, Hybrid, HyDRA