Dynamic molten pool behavior of pulsed gas tungsten arc welding with filler wire in horizontal position and its characterization based on arc voltage

To explore the dynamic behavior of molten pool and to find the electric characteristic signals reflecting the weld penetration states and degree for the fixed-point wire-filled pulsed gas tungsten arc welding (GTAW-P) of thin pipes in 2G position, molten pool images from different directions and arc voltage were sensed. During a peak current period, critical penetration occurred, with the molten pool behavior that the topside molten pool height collapsed sharply and was approximately 0.5 mm, and then rose to approximately 1.5 mm during the next base current period. With the increase in backside molten pool width, the oscillation amplitude and frequency of topside molten pool during the base current period increased and decreased, respectively. The oscillation amplitude reached the maximum when over penetration occurred. Such molten pool behaviors could be extracted from the arc voltage signals. The change in average peak voltage (Delta U*) could reflect the occurrence of critical penetration. The average base voltage ((U-b ) over bar) and the fluctuation of base voltage (Delta U-b) increased linearly with the increase in backside molten pool width, which are reliable characteristic signals for the weld penetration degree. The effects of wire filling and base current on the dynamic molten pool behavior and characteristic signals were investigated. Experimental results showed when the base current is 10 A-15 A, (U-b) over bar and Delta U-b can effectively characterize the weld penetration degree.

Automated summary

This study explores the dynamic behavior of the molten pool and identifies electric characteristic signals that reflect the weld penetration states and degree in 2G position for fixed-point wire-filled pulsed gas tungsten arc welding. The molten pool behavior, such as collapse and rise in molten pool height and changes in oscillation amplitude, can be extracted from arc voltage signals. Changes in average peak voltage and base voltage can reflect the occurrence and degree of weld penetration. Wire filling and base current have significant effects on the molten pool behavior and characteristic signals.