Aspects of ion irradiations to study localized deformation in austenitic stainless steels

The effect of irradiation depth on localized deformation in strained SUS304 and SUS316 was assessed by irradiation to various doses using different energies of Fe++ and protons. The average height and spacing of slip steps formed on the surfaces after 2% plastic strain in 300 °C argon were characterized using AFM and SEM. The step height and spacing were nearly unchanged for irradiation depth greater than 1/3 of the average grain size. 2.8 MeV Fe++ irradiation, with an irradiation depth of <1 μm, resulted in slightly larger step spacing compared to the unirradiated samples but it was much smaller compared to that in proton-irradiated samples with much greater irradiation depths. Step height and spacing also appeared to be affected by the grain size as they were nearly double in magnitude for 30 μm compared to 14 μm grain sizes in SUS304.