Close-up of welding procedure.

Hybrid laser-arc welding (HLAW)

One of the most powerful laser welding stations in the Nordic Countries is part of the National research infrastructure for manufacturing, MANULAB, jointly owned by SINTEF and NTNU. In this station we have investigated the influence of several welding parameters in HLAW welding of a thick carbon steel plate, and a first successful weld has been achieved. It is worth mentioning that the Minister of Higher Education, Ola Borten Moe, visited MANULAB and the laser station on November 15.

The principle of HLAW welding is a combination of laser beam and arc welding, as illustrated in the figure (a). The main advantages of the method are high productivity and cost-efficiency, suitable for serial production. More specifically, this includes a deep and narrow weld penetration, low heat input, minimal
weldment distortion, a high welding speed, good gap-bridging ability with a potential of a high-quality weld. However, there are challenges including cracking and porosity, lack of fusion and process stability.

Figure A: The principle of the weld method

During this process, the effects of several weld parameters were investigated including welding speed,
air gap, position of the arc, preheating and type of filler wire. A full-penetration, defect-free weld has been achieved, see figure below (b).

Figure B: A successful full penetration weld in a thick steel plate

We have proven that the method may be applicable for the fabrication of substructures on a relevant material. However, the research is still in an initial phase and hence at a low TRL (2-3). Our aim is to develop the technology for higher technology readiness levels and finally to an industrial pilot.