Fiber laser welding of 780MPa high strength steel Available to Purchase

A 2kW Ytterbium fiber laser, YLR-2000, was used for welding of 780MPa grade high strength steel. In the present work, this high strength steel is a kind of heat rolled, fine microstructure low carbon high strength steel used for welded constructions. The effects of defocusing distance, welding speed, shielding gas and its flow rate on cross section bead shape and penetration were studied in continue wave laser beam welding. The effects of frequency and duty cycle on the cross section bead shape and penetration were also studied in pulse fiber laser beam welding. In the fiber laser welding, square wave and triangle wave power output were adopted. The results showed that the pulse frequency and duty cycle of laser power had affected the bead shape and penetration in square wave Fiber laser welding. The pulse frequency of laser power had not effect on the bead width and penetration in triangle wave fiber laser welding. The microstructures of weld metals in different heat input were observed by optical microscopy. The hardness of welds was also tested and compared among welds welded at different welding speeds, in other words, in different heat inputs.