Development of new embrittlement trend curve based on Japanese surveillance and atom probe tomography data

Abstract

• A new embrittlement trend curve based on Japanese surveillance data was developed. • A simple analytical solution of the embrittlement trend curve (ETC) can be obtained from the original differential equation. • The new ETC can predict microscopic and macroscopic changes caused by neutron irradiation. We have developed a new embrittlement trend curve (ETC) for neutron-irradiated reactor pressure vessel(RPV) steels based on Japanese surveillance and material test reactor data. Our model is based on experimental data obtained by atom probe tomography (APT) and Charpy V-notch impact tests. The square root of the volume fraction ( V f ) of the solute atom cluster (SC) formed by neutron irradiation, which is determined by APT, is correlated to the Charpy transition temperature shift ( ΔT 41J ). In addition to the ΔT 41J and V f data, other APT data (the average volume of solute clusters (SC), the number density of SC, and the matrix Cu content in RPV steels) were also used to calibrate the coefficients in the new ETC model. The new ETC model has a simple functional form and, unlike the current version of JEAC4201, does not require numerical time integration. The new ETC model has similar ΔT 41J prediction performance to the current JEAC4201 model. Furthermore, the APT data are also predicted well, which suggests a good physical basis for the new ETC.