Product Code: ICA10_201
Utilizing of Laser-GMA Hybrid Welding in Industrial Application
Jukka Siltanen, Rautaruukki Oyj; Fl-1330 Hämeenlinna Finland
Presented at ICALEO 2010
The use of ultra high strength steel (UHSS) is increasing in the engineering industry and many steel manufacturers are focusing more on its production. It is easy to predict that the trend is to have even higher strength steel available on the market. Further processing of UHSS needs special attention, espe-cially the bending and welding of it can be very challenging. Typical applications in heavy engineering where the use of UHSS brings clear benefits are in the structures of load handling and transportation ve-hicles and lifting equipment such as telescopic booms or cranes. The benefits that the use of UHSS brings are a higher pay load, a longer structural lifetime and lower emissions with energy savings. This paper presents the main results of a project in which the processing of long and formed parts (up to 10 meters) made of steel Optim 960 QC was researched. This kind of structure is typical for a telescopic boom. Op-tim 960 QC is the trade mark for the steel with a yield strength of 960 MPa made in Raahe by the Finnish steel mill Rautaruukki Oyj. Several targets were set for the research. These include determining the fol-lowing: the quality level of bending and what kind of effect that will have to the laser gas-metal arc (GMA) hybrid welding; what kind of welding fixture is needed; and how to promote investment in the laser technology. The welded joint type was a butt joint with the dissimilar material thicknesses 4 and 5 mm. Laser-GMA hybrid welding tests were conducted using an IPG fiber laser with maximum 10 kW laser power, an ESAB Aristo GMA power source and Precitec welding optics. A comparative welding test with pure gas-metal arc welding was also performed. The power source used in the arc welding test was a new model with good arc pulsing properties that makes it possible to achieve a low value of heat input. The dimensions of the bent profiles were measured before and after welding. The mechanical prop-erties of the welded joints were tested with both non-destructive and destructive methods in accordance with the standards EN-ISO 15614-1 and EN-ISO 15614-11. The results show that both the accuracy and the mechanical properties of laser hybrid welded products are mostly better than those of GMA welded joints. The achieved welding speed 2.3 m/min of the laser-GMA hybrid welding is clearly faster than the welding speed 1.0 m/min of GMA welding.
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