The role of irradiation-induced phosphorus segregation in the ductile-to-brittle transition temperature in ferritic steels

The contribution of neutron irradiation-induced intergranular phosphorus segregation (RIS) to ductile-to-brittle transition temperature (DBTT) shift in reactor pressure vessel (RPV) steels is investigated in this study. A new model is presented to forecast the effect of RIS on DBTT shifts. The prediction trend curves are compared with the curves from the Russian Guide and the US Reg. Guide 1.99 Ver. 2, in addition to published experimental data. It is found that the predictions from the Russian and the US Guides exhibit agreement with experimental results for the materials with high Cu content (≥0.1 wt.%) but they underestimate for the materials with low Cu content (<0.1 wt.%). The proposed model shows a good agreement with the experimental data for both high and low Cu content materials.