| 摘要 |
In a method of flaw classification on and in welds of planar or arcuate plate-shaped workpieces of uniform thickness by means of ultrasonics, the expected flaw areas of the workpiece are pre-examined manually and are then examined systematically using the ultrasound echo image method in separate cross-sectional planes. A B-scan is thus generated, and changing the position of the transducer on the workpiece and/or the transmitting direction enables defects to be located by calculating the delay time of ultrasound waves in the go-and-return directions within the workpiece under consideration of possible reflections at the rear side (8) of the workpiece. For defining the test conditions, part-specific parameters are considered, such as weld type and weld shape (e.g., double-V-weld and bell seam), weld geometry (e.g. seam angle), and part characteristics (e.g. wall thickness), whereupon with the aid of a computer into which the parameters have been inputted, a graphic representation corresponding to a B-scan is generated. In the graphic representation at least one area, in which the density of obtained reflection points per unit of area exceeds a predetermined value, is surrounded by a closed curve of second order, generally an ellipse, and the angular direction of a privileged axis, particularly the major axis of the ellipse, in relation to a reference system, the axis ratio and/or the center location are calculated. Reflection points, located opposite from each other, of a defect are detected, and the ratio between length and thickness of the defect or the orientation tendency, respectively, is calculated, whereupon at least by logically linking orientation tendency and path difference a discrimination between volumetric-type defects, planar defects and a combination of such defects is brought about.
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