921A高强碳素钢在天然流动海水中的腐蚀行为  

Corrosion Behavior of 921A High Strength Carbon Steel in Flowing Natural Seawater

作　　者：姜万珩 张奇亮 牛璐 刘梁 黄一[1,3] 徐云泽[1,3] JIANG Wanheng;ZHANG Qiliang;NIU Lu;LIU Liang;HUANG Yi;XU Yunze(School of Naval Architecture and Ocean Engineering,Dalian University of Technology,Dalian 116024,Liaoning,China;Marine Design&Research Institute of China,Shanghai 200011,China;State Key Laboratory of Structural Analysis for Industrial Equipment,Dalian University of Technology,Dalian 116024,Liaoning,China)

机构地区：[1]大连理工大学船舶工程学院,辽宁大连116024 [2]中国船舶工业集团公司第七○八研究所,上海200011 [3]大连理工大学工业装备结构分析国家重点实验室,辽宁大连116024

出　　处：《材料导报》2023年第18期178-185,共8页Materials Reports

基　　金：国家自然科学基金(521001055);中央高校基本科研业务费(DUT21RC3093)。

摘　　要：921A碳素钢作为海洋工程用高强钢,被广泛应用于水下海洋装备的建造。921A钢在服役期间内会遭受恶劣海洋环境以及复杂流场作用,其在流动海水中的腐蚀行为是影响水下海洋装备安全运行的重要因素。为了明晰921A钢在流动海水中的腐蚀规律,利用射流喷射系统研究了海洋工程用921A高强碳素钢在不同流速(1~8 m/s)天然海水中的腐蚀行为,并结合电化学测量、微观形貌分析和计算流体力学(CFD)仿真分析了海水中流场、传质和锈层分布对921A钢腐蚀行为的交互影响机制。实验结果表明,随着海水流速从1~3 m/s升高至5~8 m/s,钢材的腐蚀损伤形貌由“流痕”转变为点蚀,海水流速增加会导致更为致密的球状锈层形成。921A钢在流动海水中的腐蚀行为受到流速、传质、壁面切应力、正应力和锈层的协同作用,锈层积累和局部腐蚀更倾向于出现在同时具有低流速、低切应力和高正应力、高传质速率特征的区域。高流速下正应力和切应力的大幅升高是导致致密锈层和点蚀形成的重要原因。921A钢的腐蚀速率在浸泡初期受活性溶解区域的发展控制,实验后期传质和锈层成为影响921A钢腐蚀速率的主要因素。在下一步工作中,将继续围绕流动海水中碳钢材料表面不同形貌锈层的形成机制与局部腐蚀发展规律开展研究。The 921A carbon steel is widely used to construct the underwater naval equipment due to its high strength.It is always subjected to harsh marine environment and complex flow conditions in its service life.The corrosion performance of 921A steel in the flowing seawater is an important factor which directly influence the safety operation of the underwater naval equipment.In order to clarify the corrosion behavior of 921A steel in flowing seawater,the corrosion performance of 921A steel in the flowing natural seawater of different flow velocities(1—8 m/s)was studied using immerged jet rig system.The influences of the flow field,mass transfer and rust layer on the corrosion behavior of 921A steel in seawater were studied using electrochemical measurement in conjunction with corrosion morphology characterization and CFD simulation.Results showed that the corrosion morphology would change from“flow mark”to pitting damage along with the flow velocity increasing from 1—3 m/s to 5—8 m/s.The increase of the flow velocity of seawater could lead to the formation of rust layer composed by much denser crystals.The corrosion performance of 921A steel is influenced by the coupled effects of flow velocity,mass transfer,wall shear steel,normal stress and rust layer.The accumulation of rust layer and initiation of localized corrosion prefer to occur at the areas of low flow velocity,wall shear stress,but with high normal stress and high mass transfer.The dramatic increases of both normal stress and shear stress at high flow velocity is the main cause for the formation of dense rust layer and pitting damage.The corrosion rate of 921A steel is controlled by the propagation of active dissolved area at the initial immersion stage.However,the mass transfer and the rust layer become the main contributor to the corrosion rate of 921A steel at the end of the test.In future studies,the formation of the different type of rust layer and the propagation of localized corrosion in flowing seawater would be focused.

关 键 词：921A钢 天然海水 流速 锈层 点蚀 CFD 

分 类 号：TG406[金属学及工艺—焊接]