酸化物分散強化鋼の高温照射環境下における強度劣化とその機構の解明

研究了核用氧化物弥散强化钢(12Crods)的组织演变和力学性能变化，系统地研究了1473~1673K高温退火对纳米颗粒粗化动力学和组织演变的影响。纳米粒子在1473K时非常稳定，在1473K时继续析出，而在1673K时则明显粗化，并且形成了不均匀分布的空洞，在1573K和1673K下保温时间较长，空洞的尺寸明显增大。这可能是由于Ar捕获和预先存在的空洞在制备条件下的生长和/或聚集。此外，在1473K时，织构没有明显变化，只是强度降低。合金的硬度在1473K时略有下降，但在1573K和1673K热处理6h以上后，硬度有明显下降。氦注入实验在东北大学回旋加速器上进行。从表面注入的氦达到390μm，浓度分别为35和70appm。在873K和973K下测试了不同应力下的蠕变性能。在973K时，氦使蠕变断裂时间和断裂应变略有降低，而在873K时，氦对蠕变断裂时间和断裂应变几乎没有影响，这表明12CrODS钢具有良好的抗氦辐照性能，这是由于12CrODS钢具有高的数密度和弥散的纳米颗粒所致。

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.