Creep and Creep-Fatigue Crack Growth Mechanisms in Alloy 709

预测在复杂运行周期和环境中长期承受应力的部件的裂纹扩展寿命是支持下一代先进核反应堆和现有反应堆（如英国先进气冷堆AGR）寿命延长的任何拟议缺陷评估程序的一个基本要素。该研究将有助于对特定不锈钢合金的蠕变-裂纹扩展、蠕变-疲劳裂纹扩展和驻留-疲劳裂纹扩展机理的科学理解。未来核反应堆中的缺陷评估程序可以更有信心地基于材料行为模型，这些模型以增加的物理理解为基础。特别是，该研究将讨论如何从加速试验中获得的结果可以适当地应用于预测在设想的操作条件下（超过60年的设计寿命）的缺陷扩展行为。

Predicting crack growth lives of components that are subject to long times under stress in complex operating cycles and environments is one essential element in underpinning any proposed flaw evaluation procedure for both next generation advanced nuclear reactors and for the extension of life of existing reactors (such as the UK fleet of Advanced Gas Cooled Reactors, AGRs). The proposed research will contribute to the scientific understanding of mechanisms of creep-crack growth, creep-fatigue crack growth and dwell-fatigue crack growth in a specific stainless steel alloy. Flaw evaluation procedures in future nuclear reactors can then be based with more confidence on models of materials' behaviour underpinned by increased physical understanding. In particular the study will address how results obtained from accelerated tests can be applied appropriately to predict flaw extension behaviour under envisaged operating conditions (over a design lifetime of sixty years).