Research On Arc Characteristic Of TIG Welding Filled By Flux-cored Wire

To meet the severe conditions of local dry underwater welding,a new process of TIG welding filled by flux-cored wire was proposed in this paper.With respect to the new process,researching its arc characteristic is necessary.Spectral diagnosis incorporated with high-speed imaging technology was employed to research arc characteristic of TIG welding filled by flux-cored wire.The fiber connected with an external long straight probe was fixed on the two-dimensional moving slide to realize the spatial fixed-point spectral acquisition and obtain the spectral information.By analyzing the collected spectral information,the active elements K and Na of the powder were tracked to determine the distribution of the powder composition.Boltzmann graph was used to calculate the temperature distribution.The effects on the arc characteristics of changing the horizontal distance between wire and tungsten electrode(ie.changing the droplet transfer mode)and adjusting current were studied.The results showed that the active elements K and Na of the powder were in the arc space above molten pool,and their distribution was affected by the horizontal distance between wire and tungsten electrode tip.The smaller distance means the closer distribution of active elements to tungsten,which leads to the tungsten electrode polluted.Compared with traditional TIG welding,the distortion of arc temperature distribution was influenced by different droplet transfer modes.The temperature distribution severely distorted under droplet transfer mode companied with more spatters during welding.A uniform temperature distribution and stable welding process occur in slag column transition and bridging transition which are suitable for the proposed TIG welding process.The size of arc temperature distribution was affected by the current.The higher current means the bigger size of arc temperature distribution,which indicates that the increase of welding current has little effect on the arc heat input per unit area,which is mainly due to the increase of arc heat input area.