Real-Time Radiographic Investigation of Weld Pool Depression

Real-time radiography has been utilized by us previously as a vision system in remote arc welding process monitoring [1]. Direct information on weld penetration extracted from real-time radiographic images of the solidified weld was used in feedback to adjust the welding conditions to maintain weld quality [2]. The disadvantage of this method is the time (and space) delay in extracting information on weld penetration which leads to the appearance of small weld areas with lack of penetration. In subsequent work weld penetration was controlled by the use of radiographic information on weld pool depression to eliminate the time delay thus providing feedback before weld solidification [3]. In this implementation the method was applied to control bead-on-plate weld penetration only with no weld joint involved. A weld made on a joint which must be filled by liquid metal during welding is more complicated than a bead-on-plate weld