Loss of fracture resistance due to thermal aging degradation is a potential limiting factor affecting the long-term (80+ year) viability of nuclear reactors. To evaluate the effects of decades of aging in a practical time frame, accelerated aging must be employed prior to mechanical characterization. In this study, a variety of chemically and microstructurally diverse austenitic stainless steels were aged between 0 and 30,000 h at 290–400 °C to simulate 0–80+ years of operation. Over 600 static fracture tests were carried out between room temperature and 400 °C. The results presented include selected J-R curves of each material as well as K_0.2mm fracture toughness values mapped against aging condition and ferrite content in order to display any trends related to those variables. Results regarding differences in processing, optimal ferrite content under light aging, and the relationship between test temperature and Mo content were observed. Overall, it was found that both the ferrite volume fraction and molybdenum content had significant effects on thermal degradation susceptibility. It was determined that materials with >25 vol% ferrite are unlikely to be viable for 80 years, particularly if they have high Mo contents (>2 wt%), while materials less than 15 vol% ferrite are viable regardless of Mo content.

由于热老化退化导致的抗断裂性丧失是影响核反应堆长期（80 年以上）生存能力的潜在限制因素。为了在实际时间框架内评估数十年老化的影响，必须在机械表征之前采用加速老化。在这项研究中，各种化学和微观结构不同的奥氏体不锈钢在 290–400 °C 下老化 0 到 30,000 小时，以模拟 0–80 多年的运行。在室温和 400 °C 之间进行了 600 多次静态断裂试验。呈现的结果包括每种材料的选定JR曲线以及K _0.2mm断裂韧性值与时效条件和铁素体含量相对应，以显示与这些变量相关的任何趋势。观察了关于加工差异、光时效下的最佳铁素体含量以及测试温度与 Mo 含量之间的关系的结果。总体而言，发现铁素体体积分数和钼含量都对热降解敏感性有显着影响。已确定，铁素体 > 25 vol% 的材料不可能存活 80 年，特别是如果它们具有高钼含量（> 2 wt%），而铁素体低于 15 vol% 的材料无论钼含量如何都是可行的。