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- ウズデンリュウ シケン ニ ヨル チュウテツ ヒョウメン キンボウ ニ オケル キズ ノ ケンシュツ
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Eddy Current Testing (ECT) was applied to non-destructive evaluation of artificial cracks, 0.25 mm in width made by electro discharge method, and internal defect, 1.6 mm diameter drill hole under the surface, in cast iron. It is important to select suitable frequency and coil for measurement to receive higher SIN signal, because small skin depth caused by ferromagnetism of a matrix limits measurable depth and inhomogeneous structure produces strong noise signal. Measurable crack depth was less than 3 mm when using two coil method. Direction of the crack could be determined from Lissajous patterns of the ECT signal. The signal changed linearly when two coils set in right angle to the crack, but showed curve when two coils set parallel with the crack. On the other hand, detection of internal defect of cast iron was difficult because change in Lissajous patterns of the ECT signal by a drill hole under 0.5 mm from the ground surface was weak as compared to higher noise signal induced by inhomogeneous matrix.
- Journal of Japan Foundry Engineering Society
Journal of Japan Foundry Engineering Society 77 (12), 821-825, 2005
Japan Foundry Engineering Society