应力腐蚀开裂(SCC)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，而SCC扩展是裂尖微观力学和电化学反应交互作用下的氧化膜破裂与再生成过程。近年来的研究显示，裂尖高应力区的蠕变对SCC裂尖氧化膜的破裂有一定的影响。为了了解焊接接头区高应力条件下裂尖蠕变特性及其对SCC扩展速率的影响，本文借助ABAQUS有限元分析软件，详细分析了焊接接头SCC裂纹高应力蠕变前后的裂尖力学场。主要完成的工作有： (1) 以常用的核电焊接材料镍基182合金为研究对象，借助ABAQUS有限元软件及其重启动功能，对低温高应力条件下裂尖蠕变过程进行分析，得到了裂尖微观力学场及相关力学参量随蠕变时间推进的变化规律。 (2) 以镍基182合金-热影响区-316L不锈钢的异种金属焊接接头的简化模型为研究对象，考虑材料力学性能不均匀性的影响，建立了焊接接头的裂尖数值模拟分析模型，对蠕变前后裂尖力学场的分布变化规律和蠕变情况进行分析；并对裂纹分别萌生于焊材区和热影响区时的裂尖力学场进行研究，得到初始裂纹位置对裂尖应力应变等参量的影响规律。 (3) 基于修正的氧化膜破裂预测模型(FA模型)，对低温高应力蠕变主导下的应力腐蚀裂纹尖端蠕变率及SCC裂纹扩展速率进行计算，得到了焊接接头材料力学性能不均匀性对SCC裂纹扩展速率的影响规律。

The stress corrosion cracking(SCC) is a main failure of safe-end dissimilar metal welded joints in primary circuit of nuclear power plants in service, SCC is a process of the oxide-film rupture and reformation dominated by the co-action of micro mechanics and electrochemistry at the crack tip. The recent researches indicate that the creep in high stress area at the tip of SCC would affect SCC growth rate. To understand the properties of the creep in high stress region at the crack tip and the effect of the creep on SCC growth rate, the stress and strain field at the tip of SCC in the welded joint is investigated by using ABAQUS software. The main task performed in this dissertation is as follows: (1) The creeping process at crack tip in high stress at low temperature was researched by using ABAQUS Finite Element Software and its restart function on welding material nickel based alloy 182, the variation law of micro-mechanical field and related mechanical parameters those influenced by the proceeding of creeping time was obtained. (2) Taking into account of the material heterogeneity, the numerical simulation modeled of weld joints were set up. The distribution of mechanical field and law of creep were analyzed in detail based on the simplified model of dissimilar metal welds composed of nickel based alloy 182, heat affected zone (HAZ) and stainless316L. In addition, the creeping and stress parameters were discussed when the initial cracks are located in welding metal and heat affected zone respectively. (3) The creep rate at crack tip of SCC and crack growth rate which were dominated by low temperature and high stress creep based on the improved oxide-film rupture prediction model (Ford-Andresen model) were calculated, The effect of welded joint material mechanical heterogeneity on SCC crack growth rate was acquired.