New laser process set to revolutionize high-strength steel welding

MAG (Metal active gas) welding and submerged arc welding are versatile processes usually used in the sheet metal, steel construction, and pipe industries. However, they also present some limitations.

First of all, they are very energy-hungry: due to the low intensity of the arc, a large portion of the energy expended is not actually used in the welding operation, but is instead dispersed through the component in the form of heat. As a result, the base material structure is subject to thermal damage and severe distortions, requiring costly and equally energy-intensive post-weld treatments and straightening processes to fix.

This is why the German Fraunhofer Institute for Material and Beam Technology IWS – together with the partners of the VE-MES Project – have developed an innovative solution to increase the efficiency of high-strength steel welding.

Enter the new Laser-MPNG (laser multi-pass narrow-gap) technology, which uses a high-power laser to weld the seam root. Then, a fast oscillating beam fills the welding gap with filler wire, ensuring the perfect melting between the two parts to be joined and the filler wire.

This process drastically lowers heat input per unit length, resulting in less stress on the material. “We can reduce the energy input for the component during welding by up to 80 percent, and we can lower filler material consumption by up to 85 percent compared to conventional arc processes,” explains Dr. Dittrich, head of the Laser Beam Welding group at Fraunhofer IWS. What’s more, straightening processes are completely unnecessary. This is due to the energy input being concentrated in the welding point, which ensures the surrounding areas remain comparatively cold. “As a result, we can cut production time and costs, process high-strength steel materials, and significantly improve the CO2 balance of the entire production chain,” concludes Dr. Dittrich.

Key advantages include a substantial reduction in the number of layers and seam volume, leading to higher productivity and less filler material used. Welding time and weld seam quality would benefit greatly from this technology.

Practical examples have been carried out on steel girders for indoor crane construction. With this evidence of practical suitability, the approach can now be extended to other applications, such as the production of reheaters, pipes, valves, and so on.

Fraunhofer Institute will showcase the Laser-MPNG welding process at the Hannover Messe 2022, slated for May 30 to June 2.

More details available at this link >>

Photo by Fraunhofer Institute for Material and Beam Technology IWS