Study on synchronous induction of arc plasma by laser in laser-double TIG hybrid welding

In order to realize the coupling discharge of the double-TIG arc and improve the utilization efficiency of arc energy, the synchronous induction of laser to the double-arc plasma is studied in this paper. The characteristics of arc plasma shape, electron temperature and density in double-arc welding and hybrid welding are analyzed by means of a high-speed camera and spectrum diagnosis. A physical model is established to discuss the synchronous induction mechanism. The results show that there are four typical position relations among the heat sources, leading to four plasma shape of double-arc. Among them, the synchronous induction only exists in the coupling plasma whose electron density rises by 60.64% compared with ordinary double-arc heat source. When keyhole current is generated in hybrid welding, the sum of the electromagnetic forces among the keyhole current and the two arc currents is the driving force of synchronous induction. When the driving force outnumbers the stiffness of double-arc, the synchronous induction of laser to double-arc occurs.