以应力腐蚀开裂(SCC)为代表的环境致裂(EAC)是核电一回路安全端异种金属焊接接头在服役过程中的一种重要失效形式，建立具有实际工程意义的安全端焊接接头SCC裂纹扩展寿命预测模型对核电重要结构安全评价具有重要意义。鉴于高温水环境下的核电结构材料SCC裂纹扩展行为可以被看作是裂尖微观环境下材料、腐蚀环境和力学交互作用下的氧化膜破裂和再生成过程。本论文在基于“SCC裂尖母材蠕变是造成氧化膜破裂的主要力学因素”的考虑下，以核电一回路常用的304奥氏体不锈钢为例，提出并研究建立了一种基于裂尖蠕变考虑的核电结构SCC扩展速率预测模型，完成的主要工作如下： (1) 借助滑移溶解-膜破裂理论和Ford-Andresen定量预测模型，通过对一回路高温水环境下核电结构裂尖氧化膜形貌的观测以及蠕变与氧化膜破裂理论关系的研究，提出了裂尖高应力区蠕变是造成“脆性”氧化膜破裂的“假说”，在此基础上推导建立了高温水环境下蠕变致膜破裂的304奥氏体不锈钢SCC扩展速率定量预测模型。 (2) 基于直流电位降(DCPD)、应变测试及数值模拟相结合的方法来测量常温下试样蠕变变形，并在此基础上推导了高温下电位降与蠕变量的关系，进而在高压釜模拟的一回路水环境中进行了304奥氏体不锈钢不同应力下的单轴拉伸蠕变实验，得出了不同应力下蠕变量随时间的演化曲线以及蠕变本构方程。 (3) 基于CT断裂力学试样，建立了裂尖区域的蠕变分析有限元模型，在此基础上分析了不同宏观结构参量对裂尖蠕变场的影响，建立了裂尖蠕变率的定量计算方法，并对SCC扩展速率的各种影响因素进行了分析。 (4) 利用本文建立的SCC裂纹扩展速率预测模型与高温水环境下实验数据进行对比分析，建立了焊接接头的简化有限元计算模型，研究了核电一回路安全端焊接接头焊缝-基体界面处裂纹以及靠焊缝一侧裂纹的蠕变对裂尖力学场以及蠕变过程对裂纹扩展速率的影响，分析得出非匀质焊接接头中SCC裂纹扩展的规律。

Environmentally assisted cracking (EAC) represented by stress corrosion cracking (SCC) is an important mode of failure for the safety of nuclear-power plants while dissimilar metal welded joint is in the service process. It is of great significance to establish an SCC crack propagation life prediction model for the safety of welded joints with practical engineering significance in nuclear power important structural safety assessment. In view of the SCC crack propagation behavior of nuclear power structural materials in high temperature water environment can be regarded as oxide film rupture and regeneration under the interaction of material, corrosive environment and mechanical at crack tip micro-environment. In this dissertation, based on the consideration of "SCC crack tip base material creep is the main mechanical factor causing oxide film rupture", an SCC growth rate prediction model of nuclear power structure under consideration of crack tip creep is proposed and studied for 304 austenitic stainless steel, commonly used in the nuclear power circuit as an example. The main work is as follows: (1) By means of slip dissolution-film rupture theory, Ford-Andresen quantitative prediction model and by observing the oxide film morphology at the crack tip and analyzing the relationship between creep and oxide film rupture, creep in high stress zone at the tip is the main mechanical factor induced brittle oxide film rupture is proposed. Based on the theory of creep-induced film rupture in high temperature water environment, SCC quantitative prediction model of 304 austenitic stainless steel is established. (2) A measurement approach of creep deformation calibration at room temperature is established by combining direct current potential drop (DCPD), static strain and numerical simulation, and the relationship between the potential drop and creep strain at high temperature has been derived as a result. The uniaxial tensile creep experiment of 304 stainless steel under different stress in the primary water environment is simulated in an autoclave environment, and evolution curves and creep law equation are derived under the relationship between the potential drop and creep strain. (3) A Finite Element (FE) numerical model has been established based on the analysis of crack tip creep of the CT specimen in fracture mechanics, the influence of different macrostructures parameters on the crack tip creep field have been analyzed as well. Futhermore，A quantitative calculation method for the crack tip creep rate is established, and finally the various factors affecting the SCC growth rate is analyzed. (4) By comparing the new SCC crack growth rate prediction model with the experimental data in high temperature water environment, A simplified finite element calculation model for welded joints is established, and the influence of creep on the mechanical field of the crack tip and the crack growth rate during the creep process is measured when the crack initiation at the weld-base metal interface and the side of the weld, the SCC crack propagation in the mechanical heterogeneity welded joints is analyzed.