Helium and radiation defect accumulation in metals under stress

The results of investigations of radiation-induced porosity in 18-10 austenitic steel after irradiation by 40-keV He+ ions and thermo-mechanical treatment are presented. External tensile stress was shown to result in an increase in He bubble size. Helium bubble migration and accumulation on grain boundaries was observed. Bubble clusters on grain boundaries are origins of brittle failure of the material. Helium bubbles increase also during post-radiation annealing. Post-radiation deformation of the material results in a considerable increase in the release rate of implanted helium gas.