了深入研究波纹管在海洋大气环境下的腐蚀过程以及准确预测其使用寿命,在考虑局部电化学反应、O2浓度及溶液中均相反应的基础上,本文采用有限元法模拟研究了波纹管波峰和波谷在不同电解质液膜厚度下的点腐蚀速度和腐蚀坑形态,同时,为了提高计算精度,本文使用插值函数的形式直接导入拟合后的极化曲线数据作为电极表面的非线性边界条件。研究结果表明:波峰比波谷的腐蚀速度更快;随着电解质液膜厚度的增加(从10μm增加到500μm),波峰和波谷的腐蚀速度均逐渐减慢,波峰处在模拟时长为120h后的最大腐蚀速度从0.720mm/a减小至0.130mm/a,波谷处从0.520mm/a减小至0.120mm/a,两处的腐蚀速度差异逐渐减小;随着腐蚀的进行,腐蚀坑逐渐向着基体内部扩展,除了纵向扩展外,其还沿着钝化膜界面横向扩展,直至穿透整个基体。本研究为不锈钢波纹管在海洋环境下的防腐工作提供了参考。
To advance the understanding of the corrosion behavior of stainless steel bellows in marine atmospheric environments and enhance the precision of service life predictions, this study employs finite element simulations to investigate the pitting corrosion rates and pit morphologies of bellows peaks and troughs under varying electrolyte film thicknesses. The model incorporates localized electrochemical reactions, oxygen concentration, and homogeneous solution reactions. For improved computational accuracy, the fitted polarization curve data were directly applied as nonlinear boundary conditions on the electrode surface via interpolation functions. Simulation results reveal that the peak regions exhibit faster corrosion rates than the trough regions. With increasing electrolyte film thickness (from 10 μm to 500 μm), corrosion rates at both peaks and troughs decrease progressively,and after 120 hours of simulation, the maximum corrosion rate at the peaks declines from 0.720 mm/a to 0.130 mm/a, and at the troughs from 0.520 mm/a to 0.120 mm/a, with the disparity in corrosion rates diminishing over time. Furthermore, as corrosion progresses, pits propagate deeper into the substrate, exhibiting both vertical penetration and lateral expansion along the passive film interface, ultimately breaching the substrate. This research offers valuable insights for designing corrosion mitigation strategies for stainless steel bellows in marine environments.