Life Prediction of Power Plant Components

近年来，在9-12%Cr蠕变强度增强铁素体（CSEF）钢方面取得了重大进展。传统上，在电厂部件的材料开发中，可被视为抗损伤的蠕变延性受到的关注要少得多。然而，由于低损伤容限而导致的灾难性故障的风险是一个真实的挑战，特别是在存在机械和冶金约束的情况下。此外，由于电厂主蒸汽管道的循环运行频率越来越高，即启动和唐斯频率越来越高，因此，由于材料的低延展性而导致的低周蠕变疲劳失效已成为一个重要问题。本博士项目的目的是研究CSEF电厂用钢的蠕变和蠕变疲劳行为，其中考虑到受实际电厂载荷循环影响的可变延展性，通过一个全面的理论，实验和计算程序。预测组件的使用寿命将与现有电力、天然气和其他能源矢量先进控制和仪器仪表的自动化研究领域保持一致。对现有模型和评估程序进行数据采集和分析以及文献综述.候选电厂钢/焊缝（可能是MARBN）的低周疲劳行为和显微组织表征的实验研究.建立了考虑循环软化和损伤的粉末冶金、焊接热影响区循环粘塑性模型.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对状态评估的要求，应用模型进行部件评估。探索早期寿命的损坏因素，如严格的工厂操作，不良设计的影响和蠕变脆性特性。将使用成熟的设备进行高温机械测试和物理表征。理论和建模工作将使用有限元软件包ABAQUS通过用户定义的子程序进行。

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.