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.
The development of non-destructive techniques (NDT) techniques for the in-service inspection of railroad wheels and gauge corners was the main activity of the NDT division VIII. 4 at BAM over the last 2 years. For such different components, two different inspection techniques were fundamentally chosen in order to fulfil the end-user requirements. Firstly the inspection of the wheelsrim and diskshould be carried out without dismantling the wheels and using ultrasonic techniques. On the other hand, the inspection of the railroad track surface at a train speed of about 70 km/h should be guaranteed using eddy current techniques. The above-mentioned tasks were a challenge for the lab staff. The accessibility for the wheel inspection was limited due to several impassable barriers such as sand tubes, etc. Eddy current application focused mainly on the detection of head check defects occurring at the gauge corner of the rail. Investigations carried out also showed, that other types of surface defects (e.g. Belgrospis, wheel burns, short-pitch corrugations, etc.) could easily be detected. Some aspects of the inspection system as well as an overview of test results are presented in the current contribution.
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.