Mechanical degradation and damage mechanisms in radiated ODS steels: Coupling microstructural evolution with dislocation dynamics

Oxide dispersion strengthened (ODS) steels exhibit exceptional radiation resistance but the damage adaptation mechanisms under irradiation remain elusive. We combine discrete dislocation dynamics (DDD) simulations and experimental characterization to compare hot isostatically pressed (HIP), extruded, and rolled variants. TEM analysis identified Y-(Ti,Zr)–O oxides with processing-dependent size distributions: extruded and rolled specimens contained coarser, denser particles than HIP counterparts due to precipitation dynamics during annealing. Mechanical testing demonstrated inverse strength-ductility relationships across processing routes, with HIP specimens showing the lowest yield strength but highest ductility. DDD simulations correlated hot-extruded microstructures with superior irradiation hardening via maintaining the repair of defects through dislocation loop annihilation while reducing the multiplication of dislocations. A strain-dependent transition from irradiation-induced loop annihilation to dislocation multiplication governs the non-monotonic damage progression observed across all specimens. The As-extruded variant achieves optimal radiation resistance through coupled Orowan strengthening and dislocation channel suppression, establishing critical processing-microstructure-durability linkages for advanced nuclear materials.