Fundamental Study of Narrow Gap Welding with Oscillation Laser Beam

Abstract

Laser welding with oscillation laser beam enables control of the heat input distribution. In this study, we attempted to develop a narrow gap welding process with oscillation laser welding. This process is expected to prevent lack of fusion because the entire bottom of the groove can be melted by the oscillation laser. As the first step of the study, bead-on-plate welding experiments with an oscillation laser beam were performed to investigate the relationship between the welding conditions and welding results. The experiments revealed that the oscillation conditions strongly affect the welding penetration shape. It was clarified that the wire melting phenomena in oscillation laser welding differed from those of straight (non-oscillation) laser welding. Additionally, narrow gap laser welding experiments were performed to investigate the relationship between the oscillation conditions and gap width. The results confirmed the effectiveness of oscillation laser welding for narrow gap welding.

Wire deposition by a laser-induced boiling front

“…The use of filler wire in laser welding goes back to the eighties when researchers concentrated on the addition of filler wire to high power CO 2 -laser welding of thick plates [1]. Three different advantages of this method interested a number of workers in this field [2]: (i) the increase in the robustness of the laser welding process by bridging the air gap between the weld parts; (ii) the improvement of the metallurgical properties and composition of the weld metal by adding a filler wire of suitable chemical composition to the melt pool; and (iii) the ability to employ multi-pass techniques to fill heavy section workpieces, (even when using low power, less expensive lasers [3]). …”

“…Recently, wire addition was observed and analysed in more detail by applying high speed imaging [3,8]. Yamazaki et al [3] successfully examined LWFW for thick materials with beam oscillation at various frequencies and amplitudes to properly fill the gap.…”

“…Yamazaki et al [3] successfully examined LWFW for thick materials with beam oscillation at various frequencies and amplitudes to properly fill the gap. Certain mechanisms were explained for a very wide weld pool, for this specific joint configuration.…”

Hot-wire Laser Welding Process Using Laser Diode for Large-Diameter Pipe with Narrow Gap Joint

“…Multi-pass narrow gap welding processes have successfully been applied to heavy thick sections to meet the demands of high-efficiency manufacturing. Examples of this include the use of hot-wire gas tungsten arc welding [1][2][3] (GTAW) and laser narrow gap welding [4][5][6][7] for thermal power plant components. We developed a novel narrow gap welding process 8) which is combined with a hot-wire system and defocused laser beam.…”