| 研究実績の概要 |
We studied microstructural evolution and mechanical properties change of an oxide dispersion strengthened steel (12Cr-ODS) for nuclear application.
The effect of high-temperature annealing at 1473-1673 K on the coarsening kinetics of nanoparticles and microstructural evolution was systematically investigated. The nanoparticles were extremely stable and continued precipitating during annealing at 1473 K, whereas, significant coarsening took place during exposure at 1673 K. Furthermore, heterogeneously distributed voids were developed, sizes of which increased distinctly at 1573 and 1673 K for longer holding time. This is probably due to the growth and/or aggregation of Ar-entrapped and pre-existed voids in the as-fabricated condition. Additionally, no obvious changes were observed in texture at 1473 K, except that its intensity reduced. The hardness slightly decreased at 1473 K up to 24 h, however, obvious reduction was observed after annealing at 1573 and 1673 K for more than 6 h.
The helium implantation experiments were carried out in cyclotron accelerator in Tohoku University. The implanted helium reached 390 μm from the surface, and concentration was 35 and 70 appm. The creep properties were tested at 873 and 973 K with different stresses. The helium leaded to slight reduction in creep time-to-rupture and strain-to-rupture at 973 K. While it shows almost no effects at 873 k. It indicates that 12Cr-ODS steel has the good resistance to helium irradiation, which was derived from the high number density and dispersed nano-particles.
|
