[1C04-07] Stainless Steel 1

[1C07] Fundamental technology development for evaluation of thermally ageing embrittlement of stainless steel welds used as pressure boundaries in nuclear power plants

(8) Development of prediction model for spinodal decomposition

*SATOSHI MINAMOTO¹, Toshiaki Horiuchi², Hiroshi Abe³, Yutaka Watanabe³ (1. National Institute for Materials Science, 2. Hokkaido University of science, 3. Tohoku University)

Keywords:dual-phase stainless steel , thermodynamic calculation, spinodal decomposition, CALPHAD approach

In order to evaluate the effect of thermal aging under irradiation on the stability of two-phase stainless steel by spinodal decomposition, thermodynamic model including excess vacancies introduced by irradiation was introduced and evaluated the Gibbs energy change and change of diffusion constant. Then these parameters were incorporated into a Phase Field method and the two phase separation behavior in the presence of excess pores was calculated.
The behavior of two-phase separation agrees well by comparing data obtained by experimentally with no irradiation condition. From the calculations considering the excess vacancy, the tendency of acceleration of two-phase separation due to excess vacancies and the time dependency of separation size for long time irradiation condition were evaluated.