The effect of dislocation on defects in 316L stainless steel irradiated by helium

Abstract

Inhibition of the movement of helium atoms produced by transmutation reactions under nuclear irradiation can be achieved by intentionally introduced trapping sites such as dislocations in stainless steels. In order to investigate the effect of dislocations in 316L stainless steel on helium irradiation-induced defects, well-annealed 316L stainless steel specimens were cold-rolled to either 10% or 20% reduction in thickness and then annealed at 723 K for 1 h, respectively. The non-deformed, 10% and 20% deformed specimens were irradiated with helium ions at an energy of 5 keV to a dose of 5 × 10¹⁶ ion/cm² under ambient temperature. The effects of dislocations on defects generated by helium ion irradiation and helium desorption with temperature were characterized by slow positron beam Doppler broadening spectroscopy and thermal desorption spectroscopy. The results shows that dislocations have a trend to restrict the migration and aggregation of helium atoms and vacancy-type defects, and also hinder the formation of large helium bubbles.