A NEW METHOD FOR DETECTION OF DEFECTS DURING WELDING BY ULTRASONIC TESTING

摘要

The present invention provides a system and method for testing the weld during welding. The formation of the defects can be identified as and when the defect is formed and can be used for providing feedback to control the weld parameter to avoid continuance of the defect formation. It can allow the repair of the defect as soon as it starts forming without waiting for the weld to be completed fully. It eliminates the requirement for weld profile smoothening for easier interpretation of signals during the post weld testing. The method can be used for identifying vertical defects in narrow gap welding processes, lack of penetration at the root in the single and double sided welding process. This method can further be also applied when the weld is not in progress, particular in the case of double sided joints where the root is to be back gouged, or back grounded, the confirmation of the removal of defects in the root pass is ensured. The present invention uses multiple transducers, preferably three, so that each transducers is injecting the sound at different parts of the weld. The sound reflected from the welded area, weld molten area, weld molten pool, and the unwelded area from the prior weld bead reflections from the bead or a defect is received in the same transducers. The method is especially applicable for the narrow gap welding processes for finding lack of fusion defects as and when they are formed. The method is also applicable for the double sided weld for detecting the lack of penetration in the root. The method is further applicable for the single sided weld for detecting the lack of penetration in the root.