超音波速度測定によるクリープキャビティの評価

概要

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An ultrasonic techique for the evaluation of creep cavities in steel for high temperature use is proposed. By using samples taken from crept or ruptured specimens, longitudinal wave velocities in the paraller and normal propagation to the stress axis (V_<LP> and V_<LN>) were measured. Then the shear wave velocities both in the paraller propagation direction to the stress axis (V_<SP>) and in the normal propagation direction for parallel and normal polarization to the stress axis (V<SNO> and V_<SNN> respecively) were measured. These results showed that all of the ultrasonic wave veiocities decrease linearly with increasing amount of creep cavities. Wave velocities were also sensitive to the directions of the propagation and the polarization. This sensitivity suggests the usefulness of V_<LP>/V_<SP>,V_<LN>/V_<SNN> and V_<SNP>/V_<SNN> as new paramenters. The values of these three parameters were to decrease linearly with an increase of the amount of creep cavities, and the comparison among these parameters showed that the ratio V_<LP>/V_<SP> was most sensitive to the amount of creep cavities. The evaluation method of amount of creep cavities using the parameters of ultrasonic wave velocity may be useful for practical purposes because it does not require the propagation path length.
社団法人日本材料学会の論文
1990-07-15