未渗氮和渗氮38CrMoAl钢在盐雾环境中的初期腐蚀行为  

Initial Corrosion Behavior of Non-nitriding and Nitriding 38CrMoAl Steel in Salt Spray Environment

作　　者：陈跃良 张柱柱 姚念奎[2] 张勇 卞贵学 黄海亮 王安东 李军亮 CHEN Yue-liang;ZHANG Zhu-zhu;YAO Nian-kui;ZHANG Yong;BIAN Gui-xue;HUANG Hai-liang;WANG An-dong;LI Jun-liang(Naval Aviation University Qingdao Campus,Qingdao 266041,China;Shengyang Aircraft Design and Reaseach Institute,Shenyang 110035,China)

机构地区：[1]海军航空大学青岛校区,山东青岛266041 [2]沈阳飞机设计研究所,沈阳110035

出　　处：《表面技术》2021年第1期383-394,共12页Surface Technology

基　　金：山东省高等学校“青创科技计划”资助项目(2020KJA014);中国博士后科学基金(2019M653929)。

摘　　要：目的研究未渗氮和渗氮38CrMoAl钢在模拟海洋大气环境中的初期腐蚀特征和电化学腐蚀行为。方法通过对未渗氮和渗氮38CrMoAl钢试件进行盐雾试验来模拟其在海洋大气环境中的初期腐蚀行为,并对不同腐蚀周期后的试件进行表面形貌、腐蚀速率、FT-IR、动电位极化、电化学阻抗和微区电化学分析及研究。结果在盐雾试验中未渗氮试件由点蚀逐渐发展为均匀腐蚀,渗氮件始终呈现局部腐蚀特征,且渗氮件的腐蚀速率小于未渗氮件的腐蚀速率。未渗氮和渗氮试件的腐蚀产物中均含有Fe_3O_4、α-FeOOH、γ-FeOOH和δ-FeOOH,渗氮件腐蚀产物层中γ-FeOOH的含量较低。未渗氮件的自腐蚀电流密度随腐蚀时间呈增大-减小-增大的趋势,容抗弧半径呈减小-增大-减小的趋势,腐蚀6 d时,未渗氮件的自腐蚀电流密度为147.83μA/cm~2,腐蚀反应电阻为2103.6?·cm~2,此时试件的腐蚀速率最低,致密的腐蚀产物层阻碍了腐蚀溶液和氧气向金属基体的扩散过程。渗氮件的自腐蚀电流密度呈增大-减小的趋势,容抗弧半径呈减小-增大的趋势,盐雾腐蚀12d后,渗氮件的自腐蚀电流密度为35.76μA/cm~2,腐蚀反应电阻为3021.5?·cm~2,渗氮件腐蚀产物层对腐蚀速率的抑制作用出现得更晚。未渗氮件在盐雾腐蚀初期,表面SKP电位差迅速增大,试件表面形成了明显的阴极区和阳极区,随后电位差保持平稳,试件表面腐蚀向均匀腐蚀发展。渗氮试件表面电位分散程度更大,局部腐蚀特征更加明显。结论未渗氮件腐蚀产物层的保护性能随厚度的增加而增加,但随着腐蚀时间的延长,腐蚀产物覆盖层不断增厚,由于内应力增加,腐蚀产物出现裂纹,使腐蚀产物层的保护性能下降。渗氮件在盐雾腐蚀初期起主要保护作用的是表面渗氮层,随着腐蚀的进行,渗氮层被逐渐侵蚀甚至出现裂纹,腐蚀产物层逐渐起主导作用。In order to study the initial corrosion characteristics and electrochemical corrosion behavior of as-received and nitrided 38CrMoAl steel in salt spray environment.The salt spray test was performed on the as-received and nitrided 38CrMoAl steel specimens to simulate its initial corrosion behavior in the marine atmosphere,and the surface morphology,corrosion rate,FT-IR,and FT-IR of the specimens after different corrosion cycles Potential polarization,electrochemical impedance and micro-area electrochemical analysis and research.In the salt spray test,the as-received specimens gradually developed from pitting corrosion to uniform corrosion.The nitrided parts always showed local corrosion characteristics,and the corrosion rate of the nitrided parts was less than that of the as-received parts.The corrosion products of as-received and nitrided specimens contain Fe3O4,α-FeOOH,γ-FeOOH andδ-FeOOH,and the content ofγ-FeOOH in the corrosion product layer of nitrided parts is relatively low.The self-corrosion current density of as-received parts showed an increasing-decreasing-increasing trend,and the capacitance arc radius showed a decreasing-increasing-decreasing trend.When corroded for 6 days,the self-corrosion current density of as-received parts was 147.83μA/cm2,the corrosion reaction resistance is 2103.6Ω·cm2.At this time,the corrosion rate of the specimen is the lowest,and the dense corrosion product layer hinders the diffusion process of the corrosion solution and oxygen into the metal matrix.The self-corrosion current density of nitrided parts showed an increase-decrease trend,and the capacitance arc radius showed a decrease-increasing trend.After 12 days of salt spray corrosion,the self-corrosion current density of nitrided parts was 35.76μA/cm2,The corrosion reaction resistance is 3021.5Ω·cm2,and the corrosion product layer of the nitrided part appears to inhibit the corrosion rate later.In the early stage of salt spray corrosion,the SKP potential difference on the surface of the as-received piece incre

关 键 词：38CrMoAl 渗氮钢 盐雾试验 微区电化学 电化学阻抗谱 腐蚀机理 

分 类 号：TG172[金属学及工艺—金属表面处理]