Nuclear grade 304 stainless steel was irradiated by 3.5 MeV Fe ions, with fluxes of 3.05E+15 ions/cm² and 1.55E+16 ions/cm². Irradiation effects were studied by positron annihilation spectroscopy (PAS), transmission electron microscope (TEM) and nanoindentation techniques. PAS results showed that different types of defects were produced after irradiation and that there was significant variance in defects formed when the samples were subjected to different irradiation doses. TEM characterization showed that the irradiation-induced dislocation loops enlarged in average size, but decreased in number density at higher irradiation doses. Nanoindentation test showed obvious irradiation hardening phenomenon, which was in good agreement with the PAS and TEM results. Irradiation hardening effect increased with an increase in irradiation dose and saturation occurred with an increase in irradiation dose from 3.2 to 16 dpa. Further statistical analysis showed that barrier strength of the Frank loop depends on the loop size and density produced by the ion irradiation.

用3.5 MeV Fe离子辐照核级304不锈钢，其通量分别为3.05E + 15离子/ cm ²和1.55E + 16离子/ cm ²。通过正电子an没光谱法（PAS），透射电子显微镜（TEM）和纳米压痕技术研究了辐照效果。PAS结果表明，辐照后会产生不同类型的缺陷，并且当样品经受不同的辐照剂量时，所形成的缺陷存在显着差异。TEM表征表明，在较高的辐照剂量下，辐照引起的位错环的平均尺寸增大，但密度减小。纳米压痕试验显示出明显的辐射硬化现象，与PAS和TEM结果吻合良好。辐照硬化效果随辐照剂量的增加而增加，饱和随着辐照剂量从3.2 dpa到16 dpa的增加而发生。