Product Code: ICA13_904

Hybrid Laser Welding of Cladded Tubes.
Authors:
Frederic Coste, PIMM-UMR 8006; Paris France
Presented at ICALEO 2013

The use of cladded pipe-lines with an inner layer of stainless steel or Nickel base alloys tends to increase for deep offshore pipe line applications. End users and certification code generally ask for conventional welding. This ensures an optimum quality on the inner side of the root pass and preserves the anti-corrosion property of the inner clad. However, this is obtained with a small thickness of the first pass and a low welding speed. Laser hybrid welding seems to be an attractive technique for increasing both the thickness of the root pass and the welding speed. Combination of a high penetration with the laser, and the use of an adapted wire should allow obtaining a root pass with a welded thickness significantly increased. A higher welding speed is also expected, compared with conventional welding.
In this study we will investigate the effect of several parameters on the seam shape and on the chemical composition of the bottom of the welded seam. For two different clads, In 625 and 316L stainless steel, we will quantify the effect of the welding direction, the groove shape, the wire composition and the arc shape on the final chemical composition of the seam. This composition will be measured with an SEM equipped with an EDX system, and we will mainly focus on the proportion of Fe, Ni, Cr and Mo in the bottom of the weld seam.