Laser-gas metal arc (GMA) hybrid welding is fast, good for deep welding, and can be used to bridge large gaps.
However, for thicker high-strength, fine-grain structural steels, hot cracks and undesired hardness levels can occur in the welding seam. For this reason, in an interdisciplinary project scientists at the Laser Zentrum Hannover e.V. (LZH) and the 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.
Single layer laser-GMA hybrid welding: Cross-section of a weld seam of 20 mm thick high-strength, fine-grain structural steel of the grade S690QL. Photo: LZH
Experimental setup of the laser-GMA hybrid welding process with an inductive coil for preheating. Photo: LZH
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.
Thus, the steel is preheated to the desired temperature, without direct contact. The weld seams are less brittle, fracture strain values are better, and hot cracks can be avoided. With this process, steel sheets can be welded with a single-layer, and time and material can be significantly saved.
Developed for Practical Application
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.
The basis for the project was close cooperation between the material and process technicians from the LZH, and the engineers from the civil engineering and electrical engineering fields at the LUH. 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).
http://www.lzh.de/en/publications/pressreleases/2014/reliable-joining-of-high-st... - further illustration and a video
Lena Bennefeld | Laser Zentrum Hannover e.V.
New process for cell transfection in high-throughput screening
21.03.2016 | Laser Zentrum Hannover e.V.
Sustainable products: Fraunhofer LBF investigates recycling of halogen-free flame retardant
17.02.2016 | Fraunhofer-Institut für Betriebsfestigkeit und Systemzuverlässigkeit LBF
Scientists and engineers striving to create the next machine-age marvel--whether it be a more aerodynamic rocket, a faster race car, or a higher-efficiency jet...
Waveguides are widely used for filtering, confining, guiding, coupling or splitting beams of visible light. However, creating waveguides that could do the same for X-rays has posed tremendous challenges in fabrication, so they are still only in an early stage of development.
In the latest issue of Acta Crystallographica Section A: Foundations and Advances , Sarah Hoffmann-Urlaub and Tim Salditt report the fabrication and testing of...
Electrochemists at TU Graz have managed to use monocrystalline semiconductor silicon as an active storage electrode in lithium batteries. This enables an integrated power supply to be made for microchips with a rechargeable battery.
Small electrical gadgets, such as mobile phones, tablets or notebooks, are indispensable accompaniments of everyday life. Integrated circuits in the interiors...
Recent findings indicating the possible discovery of a previously unknown subatomic particle may be evidence of a fifth fundamental force of nature, according...
A nanocrystalline material that rapidly makes white light out of blue light has been developed by KAUST researchers.
25.08.2016 | Event News
24.08.2016 | Event News
12.08.2016 | Event News
30.08.2016 | Ecology, The Environment and Conservation
30.08.2016 | Power and Electrical Engineering
30.08.2016 | Life Sciences