Acoustic emission measurements during welding of a 250 mm testplate

The capability of the acoustic emission monitoring system of Prine (Gard Corporation Illinois) should be demonstrated for a multi-layer submerged arc weld of a 250 mm test plate. The question had to be answered, if the measuring system developed by Prine and the evaluation models are suitable for production control of multi-layer submerged-arc welding, respectively if defect detection with interpretation of defect type, classification of size and triangulation is possible. The Prine system works with regard to electronic equipment as well as the interpretation quite satisfactory. The agreement of the defect indication with the defects visible during welding is very well. Hot and cold cracks as well as slag inclusions were indicated and normally evaluated correctly. Pores were not detected during welding. Partly a lot of low signals were realized, especially if residual stresses (closure seam) were expected. These small indications at the sensitivity level of the system could not be precisely explained. A clear evaluation of the results will be possible after completing nondestructive and destructive testing of the weld. (orig.)