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Three dimensional analysis of growing casting effects

: Feiste, K.; Stegemann, D.; Reimcke, W.; Hanke, R.F.

Deutsche Gesellschaft für Zerstörungsfreie Prüfung e.V. -DGZfP-, Berlin; Bundesanstalt für Materialforschung und -prüfung -BAM-, Berlin:
International Symposium on Computerized Tomography for Industrial Applications 1994
Berlin, 1995 (Deutsche Gesellschaft für Zerstörungsfreie Prüfung. Berichtsband 44)
International Symposium on Computerized Tomography for Industrial Applications <1994, Berlin>
Conference Paper
Fraunhofer IIS A ( IIS) ()
3-D-Röntgenbildauswertung; 3-D x-ray image evaluation; non-destructive testing; Röntgenprüfung; x-ray inspection; zerstörungsfreie Prüfung

To analyse the quality of light metal chill castings during the casting process, a radioscopy laboratory was set up at the Institute of Nuclear Engineering and Non-Destructive Testing (IKPH, University Hannover). This test equipment enables to investigate the solidification phase, as well as the creation and the development of casting defects as a function of different process parameters. While classification of casting defects is an important part of these investigations, information about the length and position of detected casting defects in three dimensions are necesssary. This paper presents the system for three dimensional analysation of growing casting defects which was developed by FhG-IIS, Erlangen, in cooperation with IKPH. Because of the special sample geometry, in this case the x-ray images can be taken only from one Image plane in contrast to the well known axial computed tomography (ACT), where images have to be taken in incremental angle steps round the object slice unde r investigation. Two different ways to solve this problem have been installed and tested and results of the defect reconstruction will be presented. First by time dependent stereographic image evaluation in combination with intensity evaluation the growing defects will be located and a coarse shape reconstruction is performed. At the end of the solidification phase a set of images from different source positions parallel to the object-plane is evaluated by a new, iterative, planar computed tomography.