Investigation of transverse shrinkage and angular distortion caused by hybrid laser-arc welding

Abstract

Hybrid laser-arc welding (HLAW) is a joining process that simultaneously combines arc and laser welding in the same weld pool. The basic concept is to reduce the drawbacks and maximize the advantages of each individual welding process. In the present work, low-alloy steel NK: KD36 plates were welded by HLAW with the following thickness: 7, 9, 14, and 17 mm. The angular distortion and the transverse shrinkage caused by the process were investigated in the welded joint with different weld parameters. The laser-arc hybrid welding experiment was carried out using a 20-kW Yb: fiber laser, together with an arc welding machine (CO2 arc welding). The laser axis was tilted to an angle of 10°, trailing with respect to the normal of the sample surface to avoid back reflections. The arc welding torch was inclined at an angle of 40°. The distance from the focus laser to arc torch was 5 mm. This investigation has shown that the hybrid laser-arc welding offers significant advantages compared with laser welding and arc welding. Compared with the conventional arc welding process, HLAW generates a lower transverse shrinkage and less weld pass for the same plate thickness. Although the coupling of the two processes leads to an increase in the number of parameters, it is the reason for the complexity of this process.