Validation of a high resolution x-ray technique within the PARENT program

Paper i proceeding, 2014

The PARENT Round Robin Test (RRT) comprises a study of the efficiency of different nondestructive examination (NDE) techniques to detect and size stress corrosion (SCC) crack in Ni-base material. This report describes an x-ray technique that has been used for detection and characterization of these defects. The x-ray source is a 450 kV x-ray machine and the detector is CCD-based with fiber optic lens and glass fiber optic scintillation screen. The imaging area of the detector is only 27 x 27 mm but the spatial resolution is very high. The un-sharpness in the image plane is measured to be less than 0.08 mm. X-ray radiography is a volumetric method and to be able to detect cracks or parts of cracks the orientation has to be reasonably parallel with the x-ray beams. Therefor each defect is radiographed in series of projections. The projection angle is from -10° to +10°, with increments of 2°. To determine the size or the depth of the cracks a method are developed which describes the depth as function of the movement of the observed crack tip between the end positions in the series of exposures.