LZH developing new process for hybrid laser arc welding with thick wire

25 Sep 2024

ÖkoHybrid project aims to weld thick steel parts faster, more efficiently.

To improve the laser-welding of thick steel components, Laser Center Hannover (LZH) is developing a new type of process for hybrid laser arc welding with thick wire.

When welding thick sheets, large seam gaps must be bridged. Conventionally this is done in multiple layers. Researchers working on the ÖkoHybrid project want to close these gaps using fewer layers, by feeding in relatively thick wire with a diameter of 3 mm.

They say that this approach should make the joining process significantly faster and more resource efficient. They are using an additional laser beam to accelerate and stabilize the process.

As part of the “ÖkoHybrid” project, the LZH scientists are investigating welding processes on fine-grain structural steels with sheet thicknesses of up to 20 mm. To this end, they will develop and build a new type of hybrid processing head. The developers want to combine a commercially available laser beam source with an output of 3 kW and a welding power source with an output of up to 40 kW.

The welding power source is being developed by project partner ELMA-Tech. Another project partner Förster Welding Systems will realize a complete system for the hybrid welding process. And Westsächsische Hochschule Zwickau, will carry out fundamental investigations into the MSG welding process, and also test and characterize the welded joints.

Hybrid laser arc welding combines the advantages of gas metal arc welding (GMAW) of thick wire with those of laser beam welding in a common process zone. The combined processes achieve a high deposition rate and a high welding speed. The use of 3 mm thick wires allows a large amount of material to be inserted, significantly reducing the number of layers to be welded and thus increasing efficiency. The additional laser beam increases the process stability.

‘Great demand’

Fine-grained structural steels are used in ship, vehicle and pipeline construction, for example. They have a higher strength than conventional structural steels, which is why lower material thicknesses can be used. This makes it possible to use less material and consequently reduce the weight of the components.

However, the material has high demands on the welding process: for example, cooling too slowly during the welding process leads to insufficient strength and toughness. If it cools too quickly on the other hand, cracks and seams with high hardness can form. The scientists therefore want to increase the welding speed and deposition rate while maintaining the required cooling times.

The sub-project “Process development for laser beam MIG hybrid welding with larger wire diameters” is funded by Germany’s Federal Ministry for Economic Affairs and Climate Action as part of the project “Economical high-performance welding of fine-grain structural steels using laser MSG hybrid welding of larger wire diameters (ÖkoHybrid)” within the framework of the Central Innovation Programme for SMEs.