Progress in modeling irradiation-assisted non-equilibrium and equilibrium inter-granular segregation in steels is discussed. Solute drag and rate theory models for non-equilibrium segregation are compared. Reference is made to recent MD simulation work on irradiated grain boundaries in alpha iron.

Predictions of the models for phosphorus inter-granular segregation are compared with several recently published experimental data from pressure vessel steels. These are as follows. • A summary of results from field emission gun scanning transmission electron microscopy (FEGSTEM) and Auger Electron Spectrometry (AES) for a variety of dose and dose rate conditions. • A systematic survey of results from variable dose rate experiments. • Results from a recent systematic data set produced from C-Mn steel submerged arc welds.

The fits of the predictions to the observations show the strong influence of site competition from carbon on the final phosphorus inter-granular segregation level.