The selection of structural materials for elevated temperature applications relies on the availability of proper design codes based on adequate data pertaining to the properties at service-relevant loading conditions. Two of the most widely used high temperature design codes, viz, the ASME Boiler and Pressure Vessel Code and the RCC-MRx code are at variance with each other on the bilinear interaction point in the creep-fatigue interaction diagram for modified 9Cr–1Mo ferritic steel. In view of this, a detailed investigation was carried out on the creep-fatigue interaction behavior of this alloy with special emphasis on the evaluation of the creep-fatigue damage and construction of the interaction diagram. Tests were performed on two chemical variants of the steel at two temperatures (773 K and 823 K) using the strain amplitudes of ±0.25%, ±0.4%, ±0.6% and ±0.8%. Hold times of different durations in the range, 1–60 min, were imposed in the tensile and compressive peak strains to introduce the creep damage. The ASME creep-fatigue interaction diagram was observed to be a more conservative design approach for the alloy.

用于高温应用的结构材料的选择取决于基于与服务相关的载荷条件下的性能有关的足够数据的适当设计规范的可用性。两种最广泛使用的高温设计规范，即ASME锅炉和压力容器规范以及RCC-MRx规范，在9Cr-1Mo改性铁素体蠕变疲劳相互作用图中双线性相互作用点上互不相同。钢。有鉴于此，对该合金的蠕变-疲劳相互作用行为进行了详细的研究，重点是蠕变-疲劳损伤的评估和相互作用图的构建。在两种温度（773 K和823 K）下对钢的两种化学变体进行了测试，应变幅度为±0.25％，±0.4％，±0.6％和±0.8％。在拉伸和压缩峰值应变中施加1-60分钟范围内不同持续时间的保持时间，以引入蠕变损伤。观察到ASME蠕变-疲劳相互作用图是一种较为保守的合金设计方法。