The effects of thermomechanical treatment on microstructural changes and void swelling in a DT2203YO5-grade 13%Cr oxide-dispersion-strengthened (ODS) ferritic alloy have been studied following ion irradiations to a damage level of 50 dpa at 475°C with 600 appm helium gas implantation. Swelling in a solution treated and aged (STA) condition ranges from 0.07 to 0.24% due to cast-to-cast variations, whilst in a solution treated, cold-worked and aged (STCWA) condition the swelling decreases to 0.025%. Cavities are in general irregularly shaped, non-uniformly distributed and frequently attached to small yttria dispersoid particles.

The results confirm that this ODS ferritic steel exhibits low irradiation-induced swelling in the presence of high gas concentrations, as required for advanced fast and fusion reactor applications. The observed sensitivity of irradiation-induced swelling to compositional or processing variables implies that ODS ferritic alloys can be further optimized for high radiation resistance.