Effect of titanium on the void swelling behavior in (15Ni–14Cr)–Ti modified austenitic steels studied by ion beam simulation

Abstract

The void swelling behavior of (15Ni–14Cr)–0.25Ti and (15Ni–14Cr)–0.15Ti modified steels are studied using heavy ions from an accelerator. The cold worked samples have been pre-implanted with a uniform helium concentration of 30 ppm 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 damage rate of 7 × 10 −3 dpa/s at various irradiation temperatures between 700 and 970 K. The gross swelling in the implanted range is measured by step height measurements. It is found that the peak swelling temperatures and the magnitude of swelling for the alloys are different. Positron lifetime measurements of the un-irradiated alloys which are annealed at various temperatures show different TiC precipitates formation behavior. 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.