Start Date

2016 12:00 AM

Description

Nonlinear resonance ultrasonic spectroscopy (NRUS) has been widely used to determine the hysteretic nonlinearity parameter, α for mesoscopic elastic materials. The current research adopts the NRUS to characterize microscopic material damage in metallic specimens with small dimensions. The geometric limitations in these small samples greatly restrict applications of other nonlinear ultrasonic techniques such as the higher harmonic generation technique.

Two opposite edges of a rectangular plate specimen (10x10x2mm) are clamped by a specially designed holder and an excitation piezoelectric transducer is attached to one of the other edges. The excitation transducer provides a frequency sweep around a few of the natural vibration modes of the specimen while the resonant response of the specimen is detected by a laser vibrometer.

To simulate the copper-rich precipitate (CRP) formation and the associated irradiation damage in reactor pressure vessel steels, thermally aged 17-4 PH stainless steel is used to study the effects of CRPs on the measured hysteretic nonlinearity parameter, α. These results are compared to previous research [1] and it is shown that the NRUS method is quite sensitive to the microstructure changes due to copper precipitates in this material.

Language

en

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application/pdf

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Jan 1st, 12:00 AM

Nonlinear Resonance Ultrasonic Spectroscopy of Precipitation in 17-4PH Stainless Steel

Nonlinear resonance ultrasonic spectroscopy (NRUS) has been widely used to determine the hysteretic nonlinearity parameter, α for mesoscopic elastic materials. The current research adopts the NRUS to characterize microscopic material damage in metallic specimens with small dimensions. The geometric limitations in these small samples greatly restrict applications of other nonlinear ultrasonic techniques such as the higher harmonic generation technique.

Two opposite edges of a rectangular plate specimen (10x10x2mm) are clamped by a specially designed holder and an excitation piezoelectric transducer is attached to one of the other edges. The excitation transducer provides a frequency sweep around a few of the natural vibration modes of the specimen while the resonant response of the specimen is detected by a laser vibrometer.

To simulate the copper-rich precipitate (CRP) formation and the associated irradiation damage in reactor pressure vessel steels, thermally aged 17-4 PH stainless steel is used to study the effects of CRPs on the measured hysteretic nonlinearity parameter, α. These results are compared to previous research [1] and it is shown that the NRUS method is quite sensitive to the microstructure changes due to copper precipitates in this material.