镍基合金环境致裂过程中裂尖微观力学特性分析

核电站一回路压力容器、管道及蒸汽发生器等设备和结构中广泛采用镍基合金和奥氏体不锈钢,而这些材料的环境致裂(EAC)却是核电结构的主要安全隐患之一。研究表明,核电高温高压水环境中镍基合金的EAC是裂尖氧化膜破裂和再生成的一个过程。为了深入了解镍基合金EAC裂纹扩展过程中裂尖的力学状况,本文从理论和数值模拟两方面分析研究了EAC裂尖氧化膜和基体金属区域的应力分布规律,为提高定量预测高温高压水环境中镍基合金EAC扩展速率精度奠定基础。

Micro-Mechanical State at the Tip of Environmentally Assisted Cracking in Nickel-based Alloy

Nickel-based alloys and austenitic stainless steels are widely used in the structures of primary circuit of nuclear power plants. Environmentally assisted cracking (EAC) of these materials is one of the most significant potential safety hazards in the primary circuit of nuclear power plants. Researches showed that EAC in nickel-based alloy is a process of oxide film rupture and reform at the tip of EAC in the high temperature water environment of nuclear power plants. To understand the micro-mechanical state at the tip of EAC, the stress and strain in the oxide film and the base metal at the EAC tip is simulated and discussed by using a commercial finite element analysis code, which provides a foundation to improve the quantitative predication accuracy of EAC growth rate of nickel-based alloys and austenitic stainless steels in the important structures of nuclear power plants.