Tensile deformation and fracture properties of irradiated SA533B steel

Irradiation effects on the stable and unstable deformation behavior and fracture properties of SA533B steel have been studied in detail based on the equivalent true stress versus true strain curves. An iterative finite element simulation technique was used to obtain the equivalent true stress-true strain curves from experimental load-displacement data. The results showed the localized necking occurs without diffuse necking for high dose irradiated cases that showed negligible uniform ductility in engineering stress-strain curves. Slope of true stress-strain curves was still positive during the unstable necking deformation regardless of irradiation dose level, and the slope considerably varied with necking mode change rather than with irradiation dose level. The equivalent fracture stress decreased with increase in dose level up to 0.1dpa and slightly increased above dose level. The equivalent fracture strain decreased with increasing dose level up to 0.1dpa and then decreased at lower rate, but it was still high after high dose irradiation exposure even if uniform ductility was almost zero. These dose dependences of tensile fracture stress and fracture strain are related with the fact that density of irradiation induced defects increases with increasing dose and is saturated at dose around 0.05dpa.