Post-irradiation annealing effects on microstructure and helium bubbles in neutron irradiated type 304 stainless steel

• Published in: Journal of nuclear materials Vol. 239; no. 1-3; pp. 90 - 94
• Main Authors: Ishiyama, Yoshihide, Kodama, Mitsuhiro, Yokota, Norikatsu, Asano, Kyoichi, Kato, Takahiko, Fukuya, Kouji
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 01.12.1996
• ISSN: 0022-3115; 1873-4820
• DOI: 10.1016/S0022-3115(96)00465-5

Helium bubble nucleation and growth processes were studied at elevated temperatures on type 304 stainless steel which had been neutron irradiated to 1.4 × 1026 n/ m 2 ( E > 1 MeV) and annealed at 400, 550, 650 and 900°C for 1 h. After annealing, specimens for microstructural observation were prepared and observed (by transmission electron microscope (TEM).) Radiation defects were present at high density in the as-irradiated specimens and annealed out with increasing annealing temperature. Helium bubbles became visible where defects were annealed out (above 650°C). The bubbles grew preferentially at dislocations and grain boundaries. At the grain boundaries, most of the helium bubbles formed on grain boundary dislocations. It was concluded that during post-irradiation annealing, the dislocations which remained after annealing played an important role in helium bubble growth, even in the grain boundaries.