Development of a robust welding process for electron beam welding of thick plates for construction of offshore wind turbines

Abstract

Due to its high energy intensity and the associated high welding depth, electron beam welding is particularly suitable for welding steel plates with high wall thicknesses. These are used, for example, in offshore wind power systems. However, due to the cooling conditions, the required cold toughness for offshore applications is often not achieved. The aim is to develop S355 ML steels – within the EN10025 4 standard – for welding monopiles for wind turbines. For this purpose, three parameters with different energy input are developed on three steels. The tests are carried out on plates with a wall thickness of 80 mm, whereby a full penetration weld must be achieved. The resulting top and bottom bead of the welds meet the standard DIN EN ISO 13919-1. The parameters have an energy per unit length of 9.5 kJ mm−1 to 15.5 kJ mm−1. The resulting weld seams have an average width of 5.5 mm to 7.5 mm, and burn-off of the manganese alloy element is observed, particularly on the top side of the seam. In addition, T8/5 times close to the weld seam of 11 s to 27 s are estimated using a simulation.