温度对2507钢在模拟烟气脱硫冷凝液中点蚀行为的影响  

Effect of temperature on pitting corrosion behavior of 2507 steel in simulated flue gas desulfurization solution

作　　者：惠朋博 邹德宁[1] 李雨浓 李苗苗 何婵 陈浩东 HUI Pengbo;ZOU Dening;LI Yunong;LI Miaomiao;HE Chan;CHEN Haodong(School of Metallurgical Engineering,Xi’an University of Architecture and Technology,Xi’an 710055,Shaanxi,China)

机构地区：[1]西安建筑科技大学冶金工程学院,陕西西安710055

出　　处：《钢铁》2024年第2期157-163,共7页Iron and Steel

基　　金：山西省重点研发计划资助项目(202202050201019)。

摘　　要：超级双相不锈钢(SDSS)因优异的耐蚀性和卓越的力学性能以及性价比高等优势,在烟气脱硫领域具有广阔的应用前景。以2507 SDSS为研究对象,利用金相显微镜、扫描电子显微镜及电化学工作站等手段,对其在不同温度(20、40、60、80℃)烟气脱硫冷凝液中的点蚀行为进行深入研究。结果表明,当溶液温度为40℃时,试验钢的自腐蚀电位(Ecorr)为-0.078 V,自腐蚀电流密度(icorr)为5.09 mA/cm^(2),点蚀电位(Epit)为0.956 V,阻抗谱半径最大,电荷转移电阻(Rct)为54200Ω/cm^(2),频率为0.01 Hz的阻抗模值|Z|f=0.01 Hz为52036Ω,其耐蚀性最好。当溶液温度从20℃升高到80℃时,试样的Ecorr、Epit先增大后减小,icorr先减小后增大,电化学阻抗谱半径先增大后减小,Rct先增大后减小,腐蚀后点蚀坑数量先减少后增多,耐点蚀性能呈现先升高后降低的规律。分析认为这是温度对电化学过程的2个相反作用(氧含量降低的阻滞效果和离子活性增强的促进效果)的综合影响结果。当温度低于或处于40℃时,溶解氧的质量浓度减少,Cl^(-)的活性、反应能力较弱,氧含量降低的阻滞效果占主导作用。随温度升高,2507 SDSS耐点蚀性能提升。当温度高于40℃时,过高的温度会增强腐蚀性卤素离子的活性及其反应能力,Cl^(-)活性增强的促进效果占主导作用。随温度升高,2507 SDSS耐点蚀能力降低。Super duplex stainless steel(SDSS)has promising applications in flue gas desulfurization(FGD)due to its excellent corrosion resistance and superior mechanical properties as well as its cost-effectiveness.The pitting behavior of 2507 SDSS in flue gas desulphurization condensate at different temperatures(20,40,60,80℃)was studied in depth using metallographic microscope,scanning electron microscope and electrochemical workstation.The findings demonstrate that at a solution temperature of 40℃,the test steel has the best corrosion resistance with corrosion potential(Ecorr)of-0.078 V,corrosion current density(icorr)of 5.09 mA/cm^(2),pitting potential(Epit)of 0.956 V,the largest impedance spectrum radius and a charge transfer resistance(Rct)of 54200Ω/cm^(2).The impedance modulus at a frequency of 0.01 Hz|Z|f=0.01 Hz is 52036Ω.When the solution temperature was increased from 20℃to 80℃,the Ecorr and Epit of the specimen increased first and decreased,the icorr decreased first and increased,the electrochemical impedance spectrum radius increased first and decreased,the Rct increased first and decreased,the number of pitting pits after corrosion decreased first and increased,the pitting corrosion resistance of the sample increased with an increase in temperature followed by a decrease.The analysis suggests that this is the result of the combined effect of the two opposite effects of temperature on the electrochemical process(blocking effect of reduced oxygen content and the promoting effect of increased ionic activity).When the temperature is below or at 40℃,the mass concentration of dissolved oxygen decreases,the activity and reaction ability of Cl^(-)are weak,and the blocking effect of reduced oxygen content dominates.With the increase of temperature,the pitting corrosion resistance of 2507 SDSS is improved.when the temperature is above 40℃,high temperature will enhance the activity of corrosive halogen ions and their reactivity,Cl^(-)activity to enhance the promotion of the effect of the dominant role.With t

关 键 词：超级双相不锈钢 烟气脱硫 温度 电化学 点蚀电位 

分 类 号：TG178[金属学及工艺—金属表面处理]