Microstructure evolution in austenitic Fe–Cr–Ni alloys irradiated with rotons: comparison with neutron-irradiated microstructures

Irradiation-induced microstructures of high purity and commercial purity austenitic stainless steels were investigated using proton-irradiation. For high purity alloys, Fe–20Cr–9Ni (HP 304 SS), Fe–20Cr–24Ni and Ni–18Cr–9Fe were irradiated using 3.2 MeV protons between 300°C and 600°C at a dose rate of 7×10−6 dpa/s to doses up to 3.0 dpa. The commercial purity alloys, CP 304 SS and CP 316 SS were irradiated at 360°C to doses between 0.3 and 5.0 dpa. The dose, temperature and composition dependence of the number density and size of dislocation loops and voids were characterized. The changes in yield strength due to irradiation were estimated from Vickers hardness measurements and compared to calculations using a dispersed-barrier-hardening (DBH) model. The dose and temperature dependence of proton-irradiated microstructure (loops, voids) and the irradiation hardening are consistent with the neutron-data trend. Results indicate that proton-irradiation can accurately reproduce the microstructure of austenitic alloys irradiated in LWR cores.