中文摘要：

火电机组锅炉过热器蒸汽侧氧化膜在机组变工况时可能发生开裂甚至脱落,对受热面安全性构成严重威胁。以超临界锅炉T91过热器管材为研究对象,在考虑温度对金属和氧化膜热膨胀系数影响的基础上,采用多层空心圆柱体模型,对3种不同工况下机组停炉过程中蒸汽侧氧化膜的稳态应力进行数值计算和分析。通过对各应力分量以及Mises等效应力进行分析,阐明了蒸汽侧氧化膜2种可能的开裂模式,同时得出了停炉过程中变工况后的负荷相同时蒸汽温度过低或者变工况后的蒸汽温度一定而负荷过低都可能导致氧化膜因等效应力过大而开裂甚至脱落的结论。

英文摘要：

Exfoliation of an oxide scale from the steam side of superheater tubes has serious effects on the safety of thermal power plants.Considering the influence of temperature on coefficient of thermal expansion,a multi-layered hollow cylinder model was developed,and different stress components as well as von Mises equivalent stress in the steam-side oxide scale of T91 superheater tubes were then calculated under 3 different operating conditions.The calculation results show a potential for the occurrence of two distinct failure modes that may be activated by hoop stress or axial stress.It has been concluded that the failure of an oxide scale may occur due to the overlarge decrease of steam temperature or load with fixed other associated parameters.