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Abstract

- ULTRASONIC VELOCITY MEASUREMENTS WERE PERFORMED ON AUSTENITIC STAINLESS STEEL TEST-PIECES, WITH TWO DIFFERENT COMPOSITIONS, AFTER CREEP STRAINING UP TO RUPTURE. - THE APPLIED METHODOLOGY CONSIDERED THE VARIATION OF THE ULTRASONIC VELOCITY, FOR LONGITUDINAL AND SHEAR WAVES, IN TWO DIRECTIONS OF PROPAGATION : PARALLEL AND ORTHOGONAL TO THE AXIS OF THE STRESS; THE MEASUREMENTS WERE PERFORMED ON SAMPLES TAKEN FROM THE TEST-PIECES AT DIFFERENT DISTANCES FROM THE RUPTURED SECTION. THE RESULTOWED THAT THE VELOCITIES DECREASE NEAR THE RUPTURED SECTION. THE CHANGES OF THE VELOCITIES FOR WAVES WITH PARTICLES VIBRATION PERPENDICULAR TO THE STRESS AXIS ARE 2-3 TIMES SMALLER THAN FOR THE WAVES WITH PARTICLES VIBRATION PARALLEL TO THE STRESS AXIS. THIS MIGHT BE DUE TO THE PRESENCE OF GRAIN BOUNDARY MICROCRACKS PERPENDICULAR TO THE STRESS AXIS. FOR SHEAR WAVES WHICH PROPAGATE ORTHOGONALLY TO THE AXIS OF THE STRESS, THE CREEP CREATES AN IMPORTANT VARIATION IN ANISOTROPY (DEFINED AS THE VARIATION OF THE VELOCITY BETWEEN SHEAR WAVES POLARIZED PARALLEL AND ORTHOGONALLY TO THE PLANES OF THE MICROCRACKS). THIS METHODOLOGY MIGHT BE APPLIED TO THE IN SERVICE INSPECTION OF COMPONENTS. IT HAS THE ADVANTAGES OF BEING INDEPENDENT OF THE TRANSDUCERS AND OF THE INSTRUMENTATION CHARACTERISTICS AND DOES NOT NEED SUPPLEMENTARY REFERENCES, DUE TO THE USE OF THE RELATIVE MEASUREMENTS BETWEEN THE TWO POLARIZATIONS OF THE SHEAR WAVE.

Additional information

Authors: LAKESTANI F JRC-ISPRA RIMOLDI P AGIP, I , JRC-ISPRA;AGIP, I
Bibliographic Reference: PAPER PRESENTED: 3RD INTERNATIONAL SYMPOSIUM ON NON-DESTRUCTIVE CHARACTERISATION OF MAT., SAARBRUCKEN/D, OCT. 3-6, 1988
Availability: Can be ordered online
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