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Erscheinungsjahr
- 2001 (4) (entfernen)
Dokumenttyp
Schlagworte
- TOFD (1)
- Time of flight diffraction (1)
- Ultrasonic weld (1)
With the increasing of the storage capability of digitised data and the development of advanced ultrasonic equipment a characterisation of detected defects is possible without new measurements. If the A-scan is stored in a video form (rectified A-scan) or in a high frequency form evaluation techniques like SAFT or echotomography are applicable with advantage. Therefore in some of the cases an estimation of the defect size is reached by the evaluation of the ultrasonic data collected with conventional detection techniques. This is an advantage in relation to the past, because the application of a separate analysis technique is mostly not necessary, therefore time and money is saved.
In the present contribution experimental results received in the laboratory are presented. The application of the TOFD approach for defect detection and sizing of crack like defect in heavy components is demonstrated whereas the probes are coupled on the carbon steel surface as well as on the cladded surface. An important point would be the influences of the anisotropic cladding material in relation to the defect sizing using the TOFD technique. These results will be compared with those received with TR longitudinal wave probes and with shear wave probes.
Weld inspection using ultrasonic pulse-echo techniques needs high skilled operators especially if geometrical indications must be taken into consideration. A clear separation between geometrical indications and defects like cracks must be guaranteed. This requirement needs sensitive techniques like the 45(deg) shear wave technique using the mirror effect. Since more than twenty years the Time Of Flight Diffraction technique (TOFD) is still under discussion for defect sizing. But on the other hand the potential of the TOFD technique for defect detection is described in technical papers of manufacturers. The main task of examinations carried out at BAM was the comparison about the detectability of surface breaking cracks between the common methods and the TOFD approach.