深海环境下金属点蚀进程及诱导应力演化  

Pitting Process and Induced Stress Evolution of Metals in Deep-Sea Environment

作　　者：亢一澜[1,2] 秦梦斐 谢海妹 韩彬[1,2] 张茜 Kang Yilan;Qin Mengfei;Xie Haimei;Han Bin;Zhang Qian(School of Mechanical Engineering,Tianjin University,Tianjin 300350,China;Tianjin Key Laboratory of Modern Engineering Mechanics,Tianjin University,Tianjin 300350,China)

机构地区：[1]天津大学机械工程学院,天津300350 [2]天津市现代工程力学重点实验室(天津大学),天津300350

出　　处：《天津大学学报（自然科学与工程技术版）》2024年第7期741-750,共10页Journal of Tianjin University：Science and Technology

基　　金：国家自然科学基金资助项目(12072228,12021002,11890680).

摘　　要：局部腐蚀产生的应力是影响海洋服役装备寿命与稳定性的关键因素.针对深海钢材料的点蚀力学问题,采用关联腐蚀与诱导应力的方法展开研究,建立了基于Nernst-Planck传质方程的腐蚀模型与腐蚀诱导应力模型,结合COMSOL多物理场仿真软件实现了深海点蚀全进程中力-电化学信息的协同表征,其关键技术有两个,一是基于腐蚀膨胀理论给出了应力与腐蚀参量之间的联系,二是以产物堆积增厚与基底腐蚀减薄的面积比确定了腐蚀膨胀率,给出了腐蚀进程中电流密度、形貌、诱导应力等参量随时空的非线性演化规律.结果表明:空间分布上,深海环境下的腐蚀呈深挖状,蚀坑中心处的电流密度最大、腐蚀程度最深,腐蚀诱导应力存在明显的集中效应,力、电化学参量随着远离蚀坑中心呈现出发散状的削弱趋势;时序演化上,电流密度随腐蚀年限减小,腐蚀进程因此逐年放缓,然而,由于蚀坑中心尖锐程度的加剧,腐蚀诱导应力的非线性增加却愈发剧烈.在此基础上,研究了腐蚀产物形貌对应力的影响,对比了简化椭球形产物与模拟所得实际形貌产物两种情况的腐蚀诱导应力,结果表明实际形貌产物最大拉应力高于椭球形的最大应力,误差超过50%,指出点蚀研究中忽略蚀坑的深挖动力学特征会给腐蚀相关的力学研究带来偏差.Stress induced by local corrosion is a crucial factor affecting the life and stability of marine materials.In this work,focusing on the mechanical problem of pitting corrosion of deep-sea steel materials,a method for correlating corrosion and induced stress was adopted and the corrosion model and corrosion-induced stress model based on the Nernst-Planck mass transfer equation were established.Combined with the multi-physical field simulation software COMSOL,the syner-gistic characterization of mechanics-electrochemical information on the entire process of deep-sea pitting corrosion was accomplished.The two key aspects were as follows:corrosion expansion theory was used to explain the relationship between stress and corrosion parameters;corrosion expansion rate was calculated utilizing the area ratio of product stack thickening to substrate corrosion thinning,and the nonlinear evolution law of current density,morphology,induced stress,and other parameters with time and space during the corrosion process were given.The results show that in spatial distribution,corrosion in the deep-sea environment exhibits a deep excavation shape,with the current density being the hightest,the corrosion degree being the deepest and the corrosion-induced stress displaying an obvious concentration effect,while the force and electrochemical parameters reveal a scattered weakening trend,where the distance is measured from the etch pit center.Regard-ing the time sequence evolution,current density decreases over time;thus,corrosion slows down year by year. However,due to the increased sharpness of the pit center,a nonlinear increase in corrosion-induced stress becomes increasingly serious. In addition,the impact of corrosion product morphology on stress was studied,and a comparison of corrosion-induced stresses between simplified ellipsoidal products and simulated real products was performed. The results imply that the real products have greater maximum tensile stress than the ellipsoidal products,exhibiting an error of more than 50% . T

关 键 词：腐蚀力学模型 腐蚀诱导应力 腐蚀膨胀率 力-电化学时空非线性演化 点蚀 

分 类 号：TG172.5[金属学及工艺—金属表面处理]