METHOD FOR NON-DESTRUCTIVE INSPECTION OF BUBBLE DEFECTS IN CAST SLAB

摘要

To provide a non-destructive inspection method capable of quickly and accurately detecting bubbles in a cast slab by appropriately setting a luminance threshold for identifying a solidified tissue and a defect without relying on the technical skill of an inspector.SOLUTION: The non-destructive inspection method for detecting bubbles generated in a cast slab, includes the steps of: irradiating X-ray to a cast slab sample collected from a cast slab, and acquiring image data of X-rays transmitted through the cast slab sample; performing image processing of the image data, and detecting an object having a luminance value exceeding a primary threshold determined from a luminance spectrum; calculating an aspect ratio indicating the aspect ratio for each detected object, and measuring a line profile of the luminance value for an object whose aspect ratio is equal to or more than a set value so as to obtain the maximum value of luminance values; and setting the average value of the obtained maximum values of the luminance values as a secondary threshold value, and determining objects whose minor axis is equal to or more than the set value as bubbles among the objects having luminance values exceeding the secondary threshold value.SELECTED DRAWING: Figure 3