700℃含镍耐热钢是发展先进超超临界发电机组的必要条件之一，其耐热性能包括蠕变机制的研究远不如传统超临界电厂低合金钢那样充分。由于汽轮机高温构件受复杂热-机械载荷作用，多轴蠕变损伤及失效问题日益突出，而多轴蠕变损伤实质上是在复杂应力状态和多种微观机制作用下材料孔洞形核、长大、聚合所引起的蠕变断裂。基于这样一种基本观点，本课题试图构建一种适合700℃含镍耐热钢高温构件的孔洞长大多轴蠕变模型，采用理论推导、数值计算、试验验证相结合研究方法，揭示700℃等级汽轮机耐热钢多轴蠕变孔洞长大失效本质，阐明材料在蠕变条件下孔洞长大的控制机制，确立微观-宏观尺度下多机制控制孔洞长大与多轴蠕变失效行为之间的内在联系，通过深入研究蠕变机制,发展适用的模型，进而为超长工作周期的大尺寸结构蠕变寿命设计提供更加完备的解决方法和理论支撑。

700℃-grade nickel containing heat resistant steel is a prerequisite to developing advanced ultra-supercritical power plant, the heat resistant properties of which has not been more abundantly studied than the low alloy steels used in traditional supercritical power plant, especially in creep mechanism. Due to the complexity of thermal-mechanical loading on high temperature turbine component, the problem of multiaxial creep damage and failure become increasingly serious. Essentially, the multiaxial creep damage results from creep rupture basing on cavity nucleation, growth and coalescence under complex stress and multi-mechanism. According to this point of view, this research project try to raise a new multiaxial creep model of cavity growth, which is fit for 700℃-grade nickel containing alloy. The methodology of combining theoretical derivation, numerical calculation and experimental investigation will be adopted in this research. Through the adopted method, the root cause will be disclosed with regard to the multiaxial creep failure of cavity growth. The cavity growth mechanism will be illustrated under creep condition, and then the relationship between cavity growth controlled by multi-mechanism and multiaxial creep failure behavior will be established corresponding to microstructure and macrostructure scale respectively. Through the newly developed model, it will provide theoretical support and technological approach to the creep life design on long life and large dimensional component.