Study of helium bubble formation in 316L stainless steel at different temperatures

In order to further the understanding of He bubble nucleation and growth in the lower temperature regime (<600degC), an irradiation experiment was performed with 2.5 MeV He+ to 316L SS specimens (SA and CW) at 400degC and 550degC. By advantage of a special cross-sectional technique employed in the TEM observation, the depth distribution of bubbles in the specimens was investigated. The underlying mechanism of bubble nucleation and growth is studied based on the temperature dependence of bubble density and average size. It is found that there is a good agreement between the prediction of di-atomic nucleation model and our result, irradiation damage has a significant effect on bubble growth. The role of dislocation in bubble formation is also studied. (author)