Product Code: ICA10_202

Weld Seam Formation and Mechanical Properties of Girth Welds Performed with Laser-GMA-Hybrid Process on Pipes of Grade X65
Authors:
Sergej Gook, BAM, Federal Institute for Materials Research and Testing; Berlin Germany
Andrey Gumenyuk, BAM, Federal Institute for Materials Research and Testing; Berlin Germany
Michael Rethmeier, BAM, Federal Institute for Materials Research and Testing; Berlin Germany
Presented at ICALEO 2010

With the recent introduction of multi-kilowatt fiber lasers combining high beam quality with an impressive energy efficiency, it was possible to broaden the spectrum of laser beam and laser-hybrid welding applications widely.
A girth laser-hybrid process using a 20 kW fiber laser and a gas metal arc welding (GMAW) process was examined at BAM, Federal Institute for Materials Research and Testing, Berlin. The aim of this research was to obtain a stable and crack free girth process and to demonstrate the possibility of its application in pipeline construction. The experiments were carried out on 16 mm thick pipe rings with 914 mm pipe diameter of X65. As it could be shown in previous publications the rings can be welded using a girth hybrid process that is divided into two steps each in 5G position downhill.
This paper will focus on imperfections of the weld seams in the different welding positions and on the methods for their avoiding. Influences of forming gas and scanner optic parameters on the appearance of the weld root were analyzed. A serie of welding experiments with preheating was performed. Mechanical properties and weld metal microstructure for the pipe segment welds were examened for different preheat temperatures.