Feasibility study of laser welding assisted by filler wire for narrow-gap butt-jointed plates of high-strength steel

Laser welding assisted by a cold filler wire (LWCFW) and hybrid laser–gas metal arc (HLGMA) welding were applied to execute the welding of 6.63-mm-thick high-strength steel (HSS) plates. The corresponding hardness distribution, tensile strength, and micrographs of the welded HSS were experimentally obtained. Results show that LWCFW can achieve a good weld quality without the groove preparation that is usually required in HLGMA welding. A narrower fusion zone and heat-affected zone can be achieved by LWCFW as compared to HLGMA welding. However, the size of the gap in a butt joint in LWCFW is limited. It was found that when a gap of about 1 mm is used in joining 6.63-mm-thick plates in a square butt joint with 4 kW of fiber laser power and a wire diameter of 0.9 mm, an acceptable weld quality could be achieved.