Hybrid Nd:YAG laser-mag welding of thick section steel with adaptive control

Abstract

The laser-arc hybrid welding process is characterised by the simultaneous application of a focused laser beam and an arc welding source. The combination of sources can provide several benefits, one of which is to provide an increased gap bridging capability, when compared with that available from the laser source alone. Using on-line monitoring of the joint geometry and adaptive control of the hybrid welding parameters, the tolerance to joint gap and fit-up can be increased and a consistent weld quality and profile can be maintained. This paper describes the results of an exploratory study, to perform adaptive hybrid laser-MAG welding, via on-line control of the process travel speed. The work used feedback from joint gap measurements, acquired from a laser vision system, in an attempt to maintain constant weld quality, particularly in terms of weld profile, when welding samples with varying gaps. When hybrid welding was used to produce square-edge butt welds in 8mm thickness C-Mn steel, a stringent weld quality, as defined for class-B of EN-ISO13919-1, could be achieved for joint gaps as large as 1.2mm, under conditions of adaptive control. Without adaptive control, this stringent quality level could be maintained only when the joint gap was less than 0.8mm.The laser-arc hybrid welding process is characterised by the simultaneous application of a focused laser beam and an arc welding source. The combination of sources can provide several benefits, one of which is to provide an increased gap bridging capability, when compared with that available from the laser source alone. Using on-line monitoring of the joint geometry and adaptive control of the hybrid welding parameters, the tolerance to joint gap and fit-up can be increased and a consistent weld quality and profile can be maintained. This paper describes the results of an exploratory study, to perform adaptive hybrid laser-MAG welding, via on-line control of the process travel speed. The work used feedback from joint gap measurements, acquired from a laser vision system, in an attempt to maintain constant weld quality, particularly in terms of weld profile, when welding samples with varying gaps. When hybrid welding was used to produce square-edge butt welds in 8mm thickness C-Mn steel, a stringent weld q...