Frequency characteristics of weld pool oscillation in pulsed gas tungsten arc welding

A direct relationship exists between the frequency of weld pool oscillation and weld joint penetration. In this paper, a novel laser vision method to detect the weld pool oscillation frequency in traveling pulsed gas tungsten arc welding was proposed. Several experiments with varying weld joint penetrations for traveling welding were conducted, and the frequency was extracted using an image-processing algorithm. The characteristics of weld pool oscillation frequency with different joint penetrations were analyzed from two aspects: surface oscillation and internal flow of liquid metal in the weld pool. Results show an oscillated mode of weld pool surface and an internal flow of partial and full joint penetration, which indicate a single oscillation frequency. In critical joint penetration, weld pool oscillation has the features of partial and full joint penetration, and generate two oscillation frequencies. This study provides a forceful foundation for the accurate detection of different joint penetration statuses.