10 Sep 2014
Inductive preheating enables reliable, single-layer welding of high-strength, fine-grain steels.
Now, scientists at Laser Zentrum Hannover (LZH) and Leibniz Universität Hannover (LUH) have developed a hybrid welding system with inductive preheating. This process can be used for reliable, high-quality, single-layer welding of high-strength, fine-grain structural steels up to a thickness of 20 mm.
In order to increase the weld seam quality for laser-GMA hybrid welding, the Joining and Cutting of Metals Group at the LZH has expanded the process to include integrated, inductive preheating. Directly before the welding process takes place, an induction coil brings energy into a targeted area of the welding seam.
The process was developed for high-strength, fine-grain structural steels with yield strengths from 460 to 690 N/mm². Applications for the used grades S700MC, X70 and S690QL can be found in crane, pump, pipeline and bridge construction, and in offshore areas. With this process, depending on the sheet thickness, feed rates of 0.75 m/min to 2.5 m/min can be reached.
While the engineers at the LZH experimented with welding processes, the Institute for Electrotechnology and the Institute for Steel Construction (both LUH) made simulations of the preheating process, respectively the welding process, and evaluated the welding seams.
The project DOVOR – High-performance welding of high-strength, fine-grained steels with high process reliability, using a hybrid welding process with integrated preheating – was financially supported by the German Federation of Industrial Research Associations "Otto von Guericke" e.V. (AiF) and the Research Association for Steel Application (FOSTA).
About the Author
Matthew Peach is a contributing editor tooptics.org.