OBSERVATION AND EVALUATION OF SIMULATED PITTING CORROSION BY PHOTOACOUSTIC IMAGING

Photoacoustic imaging of simulated pitting corrosions has been demonst rated. Simulated pittings, columnar holes, are fabricated on a pure al uminum plate by drilling, the diameters and depths of which are 0.2-1. 0 mm and 0.5-1.5 mm, respectively. Nondestructive measurement of simul ated pittings was carried out with both front and rear surface laser i rradiation exitation. The signal intensity variation with hole diamete r and depth is interpreted semi-quantitatively by means of a simple mo del. Heat flow from the bottom of a hole to the rear surface also cont ributes to the variation.