Life Prediction of Power Plant Components

近年来，9-12%Cr蠕变强度增强铁素体（CSEF）钢取得了长足的发展。传统上，在电厂部件材料的开发中，蠕变延展性被认为是一种抗损伤性，但却很少受到重视。然而，由于低损伤容限导致的灾难性失效风险是一个真正的挑战，特别是在存在机械和冶金限制的情况下。此外，随着电厂主蒸汽管道启停循环运行频率的增加，由于材料的低延性而导致的低循环蠕变疲劳失效已成为人们关注的重要问题。博士项目的目的是通过一个全面的理论、实验和计算程序，研究蠕变和蠕变疲劳行为，考虑到CSEF电厂钢在实际电厂加载周期下的可变延性。预测组件的使用寿命将与自动化现有电力、天然气和其他能源矢量、先进控制和仪器仪表的研究领域保持一致。具体目标包括：1。数据获取和分析以及对现有模型和评估程序的文献审查。候选电厂钢/焊缝（可能是MARBN）的LCF行为和微观结构表征的实验研究考虑循环软化和损伤的PM、WM和HAZ循环粘塑性模型的建立。使用工厂运行数据并考虑典型工厂部件几何形状和工厂操作员条件评估的组件评估模型的应用。探索早期造成损坏的因素，如严重的工厂操作、不良设计的影响和蠕变脆性。高温机械测试和物理特性将使用完善的设备进行。理论和建模工作将通过用户自定义子程序使用有限元软件包ABAQUS进行。

Over the years, significant development has been made on the 9-12%Cr creep strength enhanced ferritic (CSEF) steels. Traditionally, in material development for power plant components, creep ductility, which can be treated as resistance to damage, has received much less attention. However, the risk of catastrophic failure due to low damage tolerance is a real challenge, in particular, in the situation where mechanical and metallurgical constraints are present. In addition, due to the increasing frequency of cyclic operations, i.e. starts up and shut downs for main steam pipelines of power plants, low cycle creep fatigue failure due to low ductility of the materials has become an important concern.The aim of the PhD project is to investigate creep and creep fatigue behaviour which takes into account the variable ductility for CSEF power plant steels subject to realistic plant loading cycles, through a comprehensive theoretical, experimental and computational programme. Predicting the useful life of components will align with the research area of automating existing electricity, gas and other energy vectors advanced controls, and instrumentation.Specific objectives include:1. Data acquisition and analysis and literature review on the currently available models and assessment procedure.2. Experimental investigation of LCF behaviour and microstructure characterization of the candidate power plant steel/weld (possibly MARBN).3. Development of a cyclic visco-plasticity model for PM, WM and HAZ which takes into account the cyclic softening and damage.4. Application of the model for component assessment using plant operational data and considering typical plant component geometries and plant operator requirements for condition assessment.5. Exploring early life contributors to damage such as severe plant operation, impact of poor design and creep brittle properties.High temperature mechanical testing and physical characterization will be carried out using well-established facility. The theoretical and modelling work will be carried out using finite element package ABAQUS through user defined subroutines.