Evaluation of mechanical properties of 304 ss after proton irradiation using small scale mechanical testing

Austenitic stainless steels are commonly used as structural components in light water reactors, however the performance of the components can be compromised by the harsh environment to which the materials are exposed. Irradiation induced embrittlement in particular can affect the reliability of reactor operation. Both ion beam and reactor irradiated materials can benefit from small scale mechanical testing, which is therefore seeing more widespread use. These techniques enable testing of ion-beam irradiated materials for which the irradiation depth is limited to the order of tens of microns. In this study, nanoindentation, microcompression and microtensile testing are performed on unirradiated and 10 dpa proton irradiated 304SS to understand and evaluate the change in mechanical properties due to irradiation. However, it is important for this testing to be conducted at reactor operating temperatures in order to simulate the deformation mechanisms observed in a reactor setting. Nanoindentation and microcompression testing are therefore performed from 25°C to 300°C. Yield stress, hardness, and critical resolved shear stress are found to be greater in the irradiated region than in the unirradiated region. Microtensile testing is being developed to evaluate the fracture strain of the irradiated and unirradiated 304SS. This combination of testing provides a more comprehensive view of the changes in mechanical properties of the steel due to proton irradiation.