In Situ Nondestructive Examination Of Weld Penetration

The objective of this program is to develop infrared sensing techniques to monitor and control welding penetration in gas tungsten arc and submerged arc welding processes used by the US Navy in the construction of ships. The infrared sensor will provide in-situ, nondestructive weld quality information that can be used to correct depth of penetration prior to solidification of the molten metal pool. In this project the changes in surface thermal distributions resulting from intentionally induced perturbations during the welding process were measured using a low cost infrared sensor. This information was compared with the predictions of heat transfer calculations. A control system was constructed which utilizes the results of the predictions to model and control the weld penetration process. The ability to prevent plate burnthrough for variable gap and plate thickness variations was demonstrated.