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Title: Nonlinear ultrasonic characterization of precipitation in 17-4PH stainless steel

The extension of operational lifetime of most US nuclear reactors will cause reactor pressure vessel to be exposed to increased levels of neutron radiation damage. This research is part of a broader effort to develop a nondestructive evaluation technique to monitor radiation damage in reactor pressure vessel steels. The main contributor to radiation embrittlement in these steels is the formation of copper-rich precipitates. In this work, a precipitate hardenable martensitic alloy, 17-4PH stainless steel is exposed to thermal aging treatments, and used as a surrogate material to study the effects of copper precipitates on the measured acoustic nonlinearity parameter. Previous work has demonstrated the effectiveness of these nonlinear ultrasonic (NLU) measurements in the characterization of radiation-induced microstructural changes in neutron irradiated reactor pressure vessel steels. NLU measurements using Rayleigh surface waves are performed on 17-4PH samples subjected to isothermal aging. NLU measurements are interpreted with hardness, thermo-electric power, TEM, and atom probe tomography measurements. The Rayleigh wave measurements showed a decrease in the acoustic nonlinearity parameter with increasing aging time, consistent with evidence of increasing number density of nucleated precipitates.
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Resource Type:
Journal Article
Resource Relation:
Journal Name: NDT & E International, 71:8-15
Research Org:
Pacific Northwest National Lab. (PNNL), Richland, WA (United States)
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Country of Publication:
United States
Nonlinear ultrasonic methods, Thermal embrittlement, Precipitate hardening, Nonlinear Rayleigh waves