Analysis of Ultrasonic Indications in Lack of （分析超声适应症的缺乏）.pdfVIP

ECNDT 2006 - Poster 213 Analysis of Ultrasonic Indications in Lack of Fusion Occurring in Welds Milos JOVANOVIC, Gabriel RIHAR, Welding Institute, Ljubljana, Slovenia Janez GRUM, Faculty of Mechanical Engineering, Ljubljana, Slovenia Abstract. Lack of fusion is a very dangerous weld defect in a welded structure. Because of the notch effect, a crack may further propagate under the smallest load applied. This type of defect is very difficult to detect with non-destructive testing methods. For the purpose of the present study, lack-of-fusion defects were artificially produced in a multi-pass welded joint. The aim was to find out how ultrasonic devices can sense this type of defect in a butt weld. In addition radiography was used to detect the occurrence of lack of fusion in the welded joint. In the ultrasonic examination 60° and 70° angle probes were applied. They showed lack of fusion at the opposite side-walls of the groove. A normal probe was then used to detect the occurrence of inter-run lack of fusion. The weld defects provided a multiple reflection of ultrasonic waves, which confirmed the presence of lack of fusion in a certain depth. This was additionally confirmed by an ultrasonic thickness measuring gage. Finally, micro sections of the weld were made to establish the actual location and shape of lack-of-fusion defects. 1. Introduction Non-destructive testing of welded joints comprises several methods, i.e. visual testing (VT), liquid penetrant testing (PT), magnetic particle testing (MT), radiographic test