Welding of ship structural steel A36 using a Nd:YAG laser and gas-metal arc welding

Laser welding has the potential of offering both technical and economical advantages in many applications in the shipbuilding industry. A limiting factor is currently the power level available with commercial lasers, since steel plates of more than 5 mm in thickness are used in almost every shipbuilding application. In addition, the high hardness of the welds produced using laser welding is a disadvantage compared with the requirements of existing classification society standards. It has been reported that by using a hybrid welding method in which a laser beam and a gas-metal are weld (GMAW) are are combined it is possible to weld thicker sections, because the penetration is increased. Hardness values are correspondingly lower than those using the laser process because of the increased energy input. Results of a study of hybrid high power Nd:YAG laser and GMA welding are reported. All plates were welded in a butt joint configuration. When laser and GMAW were combined into a single process, I grooves were used. The air gaps between the welded plates varied. Some tests were made using a partially grooved V joint. In these cases, the root faces were welded by a Nd:YAG laser, and the upper part of the joint was welded by GMAW. It was seen that it is possible to produce defect-free welds using these processes. Macrosections of the welds, hardness values and parameters are presented and discussed. (C) 2000 Laser Institute of America. [S1042-346X(00)00105-4].