Power plants operating at elevated temperatures mainly undergo creep-dominant creep-fatigue interaction behavior. In order to safely operate power plants for long service durations, it is very important to evaluate the creep-dominant creep-fatigue damage interactions. Therefore, in this paper, the creep-fatigue interaction lifespan was evaluated through finite element analyses. Firstly, in order to consider the prior austenite grain structure of modified 9Cr–1Mo steel, a finite element model was generated using the Voronoi tessellation method. Secondly, to reflect each nonlinear creep and fatigue damage accumulation in the grain structure, Dyson and modified Wahab damage models were employed. Pure creep and pure fatigue simulations were conducted which verified that the Voronoi tessellation model and each damage model accurately accounts for the real creep or fatigue damaging mechanisms. As a consequence, finite element analyses for creep-fatigue interaction were conducted several times for various stress conditions and new criteria for the creep-fatigue life evaluation were proposed with a concern about stress sensitivity. The results were between the conventional criteria suggested by RCC-MRx and ASME-NH code.

在高温下运行的发电厂主要经历蠕变主导的蠕变-疲劳相互作用行为。为了在长期服务期间安全运行发电厂，评估蠕变主导蠕变疲劳损伤相互作用非常重要。因此，在本文中，蠕变疲劳相互作用寿命是通过有限元分析来评估的。首先，为了考虑改性 9Cr-1Mo 钢的原始奥氏体晶粒结构，使用 Voronoi 镶嵌方法生成了有限元模型。其次，为了反映晶粒结构中的每个非线性蠕变和疲劳损伤累积，采用了戴森和修正的 Wahab 损伤模型。进行了纯蠕变和纯疲劳模拟，验证了 Voronoi 细分模型和每个损伤模型准确地说明了真实的蠕变或疲劳损伤机制。因此，针对各种应力条件对蠕变-疲劳相互作用进行了多次有限元分析，并提出了新的蠕变-疲劳寿命评估标准，同时关注应力敏感性。结果介于 RCC-MRx 和 ASME-NH 规范建议的常规标准之间。