Laser hybrid welding of tailored tubes with integrated quality analysis and closed loop process control
Modern lightweight construction using laser welding can often not be achieved for small series and prototyping due to high demand in edge preparation, positioning and clamping. The projects aim was the use of a laser-GMA-hybrid welding process for welding of zinc-coated sheet metal. Compared to laser welding, the gap bridging was increased and metallurgical modifications by the wire and the additional energy input were expected. The process was developed and analysis shows that the stability is decreased by the zinc coating. An automatic quality monitoring based on the process radiation and the current time-signal can detect instabilities. A closed loop process control system was derived from the quality monitoring allowing an increase of welding speed by 10 % at an increase of gap bridging by 12 %. The properties of hybrid welded seams were investigated and compared to the properties of laser welds. For low alloyed steel, the carbon equivalent of the filler wires causes a hardness increase. This can be overcome by adapted fil1er wires with low carbon equivalent. No significant influence of the energy input on the strength and forming properties was found. Forming investigations on welded tubes pointed out comparable forming ability of laser and hybrid welds. Tailored tubes were produced and formed showing excellent forming behaviour in the T-forming test. The corrosion resistance is lightly decreased by a wider destruction of the zinc layer on the surface. It was shown that the hybrid welding process developed in this project has the potential to allow laser welded lightweight parts, even for small series with lower tooling expenses.
Bibliographic Reference: EUR 21418 EN (2005), 152 pp. Euro: 25
Availability: http://bookshop.europa.eu/is-bin/INTERSHOP.enfinity/WFS/EU-Bookshop-Site/en_GB/-/EUR/ViewPublication-Start?PublicationKey=KINA21418 (Catalogue Number: KI-NA-21418-EN-S)
ISBN: ISBN 92-79-00056-X
Record Number: 200618448 / Last updated on: 2005-12-15
Original language: en
Available languages: en