高铬回火马氏体铁素体钢的高温蠕变变形和破坏机理研究

In this proposal, crystal plasticity based multiscale modelling and experimental investigations will carried out to study the high temperature creep deformation and fracture behaviour for high Cr martensite ferritic steels. The key objective is to analyse the physical process of deformation and fracture at mutiple length scales and quantify the microstructural effects. The research is performed in the following three aspects: crystal plasticity theory, multiscale finite element modeling framework and experimental characterisation. The following key novelties will be achieved in the research. First, the precipitate coarsening effect during creep and the microscale damage are incorporated into the crystal plasticity theory. In particular, the according governing equations for the evolving processes used in the crystal plasticity constitutive relation are based on the physical mechanisms of the precipitate coarsening and ductile creep fracture. Second, through a complete scale-connection method, the multiscale modeling framework is implemented to predict the microstructural effect and the precipitate coarsening effect on the creep properties. Third, the in-situ synchrotron measurement is used to characterise the microscale deformation and the precipitate coarsening effect, particularly, the effect of precipitate's inelasticity at high temperature will be evaluated.

本项目对高铬马氏体铁素体钢高温蠕变变形和破坏行为开展基于晶体塑性本构的多尺度计算模拟和实验研究，主要研究目标是定量分析材料高温蠕变的多尺度变形和破坏的物理过程，明确微观组织结构因素的影响规律。研究工作在晶体塑性本构理论、多尺度模拟、和实验表征三个方面展开。主要的创新点包括：在晶体塑性本构中考虑强化相粗化效应以及微观破坏，基于强化相粗化和韧性破坏的微观物理机制发展相应的控制演化方程；通过双向跨尺度关联方法建立多尺度有限元模拟框架，预测微观组织结构以及变形过程中的强化相粗化对材料蠕变性能的影响；通过原位同步辐射实验表征高温蠕变时的强化相粗化对材料微观变形的影响，与模拟结合分析强化相的非弹性效应。

马氏体耐热钢的高温蠕变性能劣化问题在我国在役火电站核心热端部件中非常突出，在带来安全隐患的同时也限制了发电效率和操作灵活度的进一步提升，在当前的研究背景下，对与纳米析出相相关高温蠕变变形和破坏机理的研究还不深入，特别是缺乏多尺度力学模型研究来定量描述马氏体耐热钢中纳米析出相及其演化对蠕变性能的影响。为此，本项目的研究工作在实验表征、宏微观本构理论和多尺度计算模拟三个方面展开，从宏观和微观两个尺度研究了马氏体耐热钢的高温蠕变变形和破坏行为，阐明了变形和破坏机理，发展了非线性力学本构模型和用于宏微观结构分析的有限元模型，定量研究了组织结构与宏观性能之间的映射关系。本项目所发展的多尺度非线性力学本构模型不但可以为直接应用于分析火电站构件的高温失效问题奠定关键基础，也可以拓展至其他领域中的同类问题中，如在高温合金装备制造领域也产生了一定的应用效果。