Multiwire submerged arc welding of steel structures

The assembly of large structures made out of thick steel plates requires a welding process by which multiple wires can be used simultaneously. To reproduce these industrial processes in a research environment, OCAS has invested in a multiwire submerged arc welding (SAW) setup. In this multiwire setup, up to five wires in tandem configuration can be used. The objective of this master thesis is to establish a deeper knowledge of process parameters used to weld steel plates in a thickness range of 12,7 up to 25 mm, by means of the submerged arc welding process. Based on literature, a test matrix is composed in which the number of wires, the plate thickness and other weld parameters are the variables. In addition, a specific plate preparation for each plate thickness is derived from the literature. The preformed weld trails will be evaluated on weld bead geometry and metallographic properties. There is further experimental examination required, which will result in the revising of the matrix

Multi-wire submerged arc welding: a study of secondary process parameters

The goal of this thesis is to investigate the effect of secondary process parameters on the geometry of the weld bead in multi-wire submerged arc welding. Bead-on-plate welding experiments will be conducted using 3, 4 and 5 wires. The parameters being varied will be the wire stick out, the angles of the torches and the spacing in between. Primary process parameters like voltage, current and welding speed will be kept constant. Penetration, bead width and height, percentage dilution, HAZ, weld penetration shape factor and weld reinforcement shape factor will be measured and evaluated. Fewer experiments will be needed because of the use of a design of experiments approach, namely a fractional factorial design. This will allow to determine the significance of each single parameter and their mutual interaction with respect to weld bead shape