Position welding of 960 MPa ultra-high-strength steel

High-strength and ultra-high-strength steels are used more and more frequently in the engineering industry. The welding of high-strength steels requires lower heat input welding processes to achieve matching joints. Laser and laser-GMA hybrid welding processes are used for the welding of these kinds of special steels. The Finnish steel maker Rautaruukki makes high-strength and ultra-high-strength steels under the trademark Optim. In earlier studies, the welding position for these steels has been a flat position (PA/1G). In this study, the welding position was a flat position, but a horizontal (PC/2G) and an overhead position (PE/4G) were also tested. The test material was an ultra-high-strength steel Optim 960 QC with a thickness of 6 mm. The laser-GMA hybrid welding tests were performed with a Trumpf 12 kW disk laser equipped with a Fronius TIME 5000 Digital GMA power source. Some comparative tests were performed using GMA welding and laser welding. The filler materials used were Esab OK Autrod 12.50 (ISO 14341, G42 G3Si1) and Union X96 (ISO 16834, G89 Mn4Ni2CrMo) with a diameter of 1 mm.