Laser hybrid welding is today a topic with special interest from both researchers of laser welding and utilizing industry. This is due to the problems of normal autogenous laser welding encountering especially in case of producing large metal structures. There are quite a few theories presented how the laser and arc welding processes form a united process. Most of the advantages gained is said to be caused by the fact that the processes act together and support each other.
Some of the phenomena occurring during laser hybrid welding were studied with the help of high speed videography by using special lighting and filtering. These results were compared to the results of experiments done by laser welding with filler wire with the same videography set-up. The material used was mild steel of thickness 6 mm and a butt joint configuration was used.
The videos show how the material is transferred from wire to melt pool or even into the keyhole. In hybrid welding, if the processes are close enough each other they act together as a united process, but with too long distance between the processes the process is tandem rather than hybrid process. If the distance between the processes is too long for the processes to have interaction with each other, the welding speed is too high for arc welding process resulting in a weld with uneven bead. In case of welding mild steels the leading torch gives more stable process in comparison to trailing torch. This is caused by the more fluent flow of melt droplets when leading torch is used. The leading torch also ensures more even weld bead.
In case of filler wire welding the wire is positioned to process such that the wire is fed into melt pool and melted by the laser beam partly inside the keyhole. The welding process with filler wire is much more stable than the laser hybrid process.