A study of the effect of titanium on the void swelling behavior of D9 steels by ion beam simulation

The void swelling behavior of D9 with 0.25Ti and D9 with 0.15Ti modified steels was studied using heavy ion irradiation. The cold worked samples were pre-implanted with a uniform helium concentration of 30 appm spanning a width of about 640 nm. This was followed by a 5 MeV nickel ion irradiation to create a peak damage of 100 dpa at a damage rate of 7 × 10−3 dpa s−1 at various temperatures between 700 and 970 K. The gross swelling up to the implanted range was measured by step height measurements. It is found that the peak swelling temperatures and the magnitude of swelling are different for the alloys studied. Positron lifetime measurements of the unirradiated alloys annealed at various temperatures show differences in the formation of TiC precipitates. The difference in void swelling behavior in these two alloys with titanium variation is discussed on the basis of the role of titanium on the vacancy migration and TiC precipitate formation.