Influence of injected interstitials on the void swelling in two structural variants of 304L stainless steel induced by self-ion irradiation at 500 °C

Two variants of AISI 304L stainless steel (SS) with different grain size distributions were ion irradiated at 500 °C to a peak dose of ∼60 dpa. In the coarse-grained annealed variant, a peak swelling of ∼12% was observed closer to the specimen surface rather than at the depth of peak displacement damage. The forward shift in depth between peak swelling and peak dose is proposed to be a consequence of suppression of void nucleation by injected interstitials. The swelling behavior in the front portion of the ion range mirrors that of neutron-induced swelling in this steel, exhibiting significant curvature with increasing dose as the swelling rate approaches the terminal swelling rate of 1%/dpa. An ultrafine grain variant of this steel produced by severely plastic deformation exhibits a similar suppression of void nucleation in the injected interstitial region, but also shows a significantly extended transient regime, not reaching the terminal swelling rate by 60 dpa.