腐蚀缺陷对921A钢力学-电化学性能的影响

针对目前舰船腐蚀电场方面的研究没有考虑舰船在服役环境中因应力应变造成腐蚀加剧的问题，基于金属/溶液的力学-电化学耦合模型，推导应力应变条件下腐蚀缺陷深度和缺陷宽度对舰船921A钢壳体及溶液应力分布，腐蚀电位、电流密度以及腐蚀电场影响规律的理论表达式，采用COMSOL Multiphysics软件对耦合模型开展仿真计算。研究结果表明：腐蚀缺陷深度越大或者缺陷宽度越小，腐蚀缺陷处的应力集中越明显；溶液中的电位差随着缺陷深度的增大而增大，金属/溶液界面的腐蚀电位随着缺陷深度的增大而急剧负移，而腐蚀电位随着缺陷宽度的减小小幅负移；缺陷深度对阳极电流密度、阴极电流密度和净电流密度的影响均大于缺陷宽度，缺陷两端点的净电流密度为负；电场模量随着缺陷深度的增大而逐渐增大，随着缺陷宽度的增大而逐渐减小。

Effects of Corrosion Defects on Mechanical-electrochemical Properties of 921A Steel

The current research on ship corrosion electric field has not taken into account the aggravation of corrosion caused by stress and strain in service surroundings. Using the mechanical-electrochemical coupling model of metal/solution, theoretical expressions of the effects of corrosion defect depth and defect width on the stress distribution, corrosion potential, current density, and corrosion electric field of 921A steel shell and solution are obtained under stress-strain conditions, and the coupling model is simulated using COMSOL Multiphysics. The results show that the stress concentration at the corrosion defect is more evident when the defect depth is greater or the defect width is smaller. The potential difference in solution increases with the defect depth; the corrosion potential at the metal/solution interface decreases sharply with the increase of the defect depth; the corrosion potential decreases slightly with the decrease in the defect width. The influence of defect depth on anode current density, cathode current density, and net current density exceeds that of defect width. Both ends of the defect have a negative net current density. The electric field modulus increases with the defect depth and decreases with the defect width.