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Progress Towards Validation and Standardization of the UT of Bimetallic and Austenitic Welds Using SH-Waves and EMAT's

: Borgenstam, C.J.; Hübschen, G.; Kröning, M.; Salzburger, H.-J.

Davidson, G.M.; Iida, K.; Ammirato, F.; Light, G.M.; Whittle, J.M. ; American Society for Metals -ASM-, Metals Park/Ohio:
NDE in the nuclear and pressure vessel industries. Proceedings of the 14th International Conference 1996
Materials Park, Ohio: ASM International, 1997
ISBN: 0-87170-548-6
ISBN: 0-87170-589-3
International Conference on NDE in the Nuclear and Pressure Vessel Industries <14, 1996, Stockholm>
Conference Paper
Fraunhofer IZFP ()
austenitic weld; austenitische Schweißnaht; SH-wave; SH-Welle; shear wave; Ultraschalltechnik; ultrasonic technique

The UT of bimetallic and austenitic welds is strongly complicated by a high degree of elastic anisotropy and the coarse grain structure of the weld material and the buttering. Due to these facts up now using standard UT-techniques only the HAZ's are inspected from both sides. In many cases bimetallic welds are only accessible from one side. Therefore techniques are necessary which are capable to inspect the whole weld even if there is only access from one side. Horizontally Polarized shear-waves (SH-waves) are less affectec b< the mentioned effects than other wave modes. They have the capability of penetration of the weld metal, buttering and also the cladding on the ferritic side. To use these advantageous features for the in-service inspection of components according to the codes and standards, investigations were performed for the determination of the relevant features of the technique, of the data of the probes and of the equipments. With the knowledge of these data, basic rules ca n be provided for the preparation, performance, documentation and accessment of the inspection. The contribution presents the results of these investigations. In the first step possible areas for the application of this technique (component, reactor type) were identified and worst case situations - geometry, accessagility, surface conditions (waveness) of the component - were defined. In consideration of these worst case situations the main data of the technique, the probes and the equipments were investigated. Recommendations and rules for the optimal application wre established and limitations were recgnized. Finally, a comparing assessment of the SH-wave technique with standard and special piezoelectric UT technqiues was performed by testspecimen measurements.