Investigations on high-power laser beam-submerged arc hybrid welding of thick duplex stainless steel using laser beam wobbling

Duplex stainless steels are used in many application fields due to their outstanding performance with respect to strength, toughness, and corrosion resistance. These properties are based on a microstructure proportion of at least a proportion of 30% austenite. To meet the requirements of the microstructure and a high productivity, a high-power and precise heat controlled welding procedure like laser beam-submerged arc hybrid welding is necessary. In this study, laser beam-submerged hybrid welding processes are developed for butt joints of duplex stainless steel S31803 (t = 16 mm) using a disk laser beam source with a maximum output laser beam power of PL = 16 kW. The aims of these developments are to achieve stable, efficient one-layer welding processes for joining weld seams with high quality regarding the microstructure. Therefore, the welding parameters, laser beam power, welding speed, and wobble amplitude are investigated using visual inspections and metallographic analyses. To increase the microstructure proportion of austenite, the laser beam is wobbled linear and transversal to the welding direction using amplitudes up to 5 mm. As results of welding process developments, stable and efficient one-layer hybrid welding processes were archived at a high welding speed of vW = 1.0 m/min and a wobble amplitude of WA = 2.5 mm. The weld seams meet the requirement of at least a proportion of 30% austenite. Without using laser beam wobbling, the weld seam does not achieve the austenite proportion required at this welding speed.