Void swelling in cold worked FV548 steel irradiated in a high voltage microscope after pre-injection with 10 ppm helium

Abstract

Abstract A study has been made of void formation in 20% cold worked FV548 austenitic stainless steel irradiated with 1 meV electrons in the Harwell AEI EM7 high voltage microscope (HVM) after pre-injection with 10 ppm helium. In the temperature range studied, the void swelling is similar in all respects to the void swelling in 1150°C solution treated FV548 steel. This is contrary to the behaviour observed during fast neutron and heavy ion irradiation, where 20% cold work markedly reduces void swelling. Limited experiments on 60% cold worked FV548 steel show that voids form readily even at this cold work level, but the void swelling is reduced by ≈50%. Subsidiary experiments have eliminated the very high dose rate and the helium content as reasons for the lack of sensitivity to cold work: it seems likely that it is related to the production of point defects in Frenkel pairs during election irradiation, as opposed to displacement cascades.