Void swelling studies of stainless steel containing silicon and titanium

Four stainless steels are irradiated in the high voltage electron microscope: nitrided 20/25/Ti; unnitrided 20/25/Ti; 316 steel, and 316 + 1% Si steel. In the unnitrided steels solute silicon reduces the number density of voids and solute titanium increases the number density of loops. These observations are analysed in terms of point defect rate theory: titanium and unspecified interstitial atoms have a binding energy of 0.85 eV, and gas atoms can be bound to silicon atoms. The rate theory does not fit the observations on the nitrided steels in any simple fashion. The trapping of gas atoms at residual dislocations associated with TiN particles appears to be a major factor in the void swelling behaviour. (author)