3-23. Multiphysics modeling on transient crevice corrosion of stainless steel

Haitao Wang, Jiawei Ding, En-Hou Han

CAS Key Laboratory of Nuclear Materials and Safety Assessment, Institute of Metal Research, Chinese Academy of Sciences, Shenyang 110016, China

Abstract: The transient crevice corrosion behavior of 304 stainless steel in NaCl solution was simulated by multiphysics coupling method. The model considers the local electrochemical reaction, the transport of different species and the homogeneous reaction. The moving mesh method is used to simulate the geometrical change of the crevice wall with time due to corrosion. The level set method is employed to quantitatively describe the precipitation process and its influence on electrochemical reaction. On the basis of passive stainless steel, the model considers the effect of pH change on the passivation-activation state transition of stainless steel. The transient crevice corrosion morphology, pH distribution, potential and current distribution, precipitation porosity distribution and ion concentration distribution were obtained by simulation. The effect of geometry factor log(r2/w) on the crevice corrosion process of stainless steel was studied. The results shows that with the decrease of log(r2/w), the possibility of crevice corrosion becomes lower, and the potential, current, ion concentration distribution within the crevice are more gradual. The simulation results are in good agreement with the experimental data, showing that the model has high reliability. This model helps to understand the mechanism of crevice corrosion and can be further extended to other related forms of localized corrosion.

Keywords:Stainless steel; Crevice corrosion; Simulation; Multiphysics; Transient behavior 

不锈钢缝隙腐蚀行为的多物理场耦合仿真模拟

王海涛，丁佳伟，韩恩厚
中国科学院金属研究所 中国科学院核用材料与安全评价重点实验室，沈阳 110016 

摘要:采用多物理场耦合仿真模拟研究了 304 不锈钢在 NaCl 溶液中的暂态缝隙腐蚀行为。模型 考虑了局部电化学反应，不同物质的传输以及均相反应，利用移动网格方法模拟了缝隙壁因腐蚀随时间发生的几何尺寸变化，采用水平集方法定量描述了沉淀过程及其对电化学反应的影响。 模型在钝态不锈钢的基础上，考虑了 pH 变化对不锈钢钝化-活化状态转变的影响。模拟得到了 暂态缝隙腐蚀形貌，缝隙内 pH 分布、电位电流分布、沉淀孔隙度分布、离子浓度分布，并且研 究了缝隙尺寸因子 log(r2/w)对不锈钢缝隙腐蚀过程的影响，结果表明，随着 log(r2/w)的减小，发 生缝隙腐蚀的可能性也越来越小，缝隙内电位和电流、离子浓度分布越来越平缓。模拟结果与 实验数据吻合较好，显示了模型具有很高的可靠性。该模型有助于理解缝隙腐蚀的机理，并可 进一步扩展到其他相关形式的局部腐蚀。

关键词:不锈钢;缝隙腐蚀;仿真;多物理场;暂态行为