稀土对UNS S31803不锈钢夹杂物变质行为及耐点蚀性能的影响  

Effect of rare earth on inclusion modification behavior and pitting corrosion resistance of UNS S31803 stainless steel

作　　者：刘晓 赵良群 葛杰 陈雷[3] LIU Xiao;ZHAO Liang-qun;GE Jie;CHEN Lei(Jiangsu Jicui Metallurgical Technology Research Institute Co Ltd,Jiangsu Metallurgical Technology Research Institute,Zhangjiagang 215625,China;College of Mechanical Engineering,Jiangsu University of Technology,Changzhou 213001,China;College of Mechanical Engineering,Yanshan University,Qinhuangdao 066004,China)

机构地区：[1]江苏集萃冶金技术研究院有限公司江苏冶金技术研究院,江苏张家港215625 [2]江苏理工学院机械工程学院,江苏常州213001 [3]燕山大学机械工程学院,河北秦皇岛066004

出　　处：《材料热处理学报》2022年第11期94-102,共9页Transactions of Materials and Heat Treatment

基　　金：国家自然科学基金(51675467);江苏省高端结构材料重点实验室开放基金(hsm1906)。

摘　　要：采用电化学阳极极化、电化学阻抗谱、光学显微镜、扫描电镜、能谱仪及夹杂物统计分析等研究了稀土(RE)对UNS S31803双相不锈钢中夹杂物的变质行为及点蚀萌生行为的影响。结果表明:稀土能提高试验钢的点蚀电位和钝化膜电阻,未加RE与加RE的钢的点蚀电位分别为726 mV与1019 mV,钝化膜电阻分别为26590Ω·cm^(2)与67170Ω·cm^(2),稀土通过降低钢中夹杂物的数量与尺寸及形成稳定的稀土氧化物且弥散分布在钢中等因素提高了其耐点蚀性能;与未加RE钢相比,加RE钢中的夹杂物数量减少了25.93%,直径为0~3μm的夹杂物数量占比增加了21.57%,直径为3~5μm、5~7μm和>7μm的夹杂物数量占比分别减少了15.99%、5.59%和4.99%;加入稀土后,试验钢中的含Cr、Al、Mn和Ti等氧化物夹杂变质为稀土氧化物;未加稀土的钢点蚀发生在氧化物夹杂与基体连接的微裂纹处,并向氧化物夹杂处扩展;而加稀土的钢点蚀发生在稀土氧化物夹杂与基体连接的微裂纹处,并向基体延伸;基于此,绘制了夹杂物对双相不锈钢腐蚀微区点蚀萌生和扩展影响的示意图。Effect of rare earth(RE) on modification behavior of inclusions and pitting initiation behavior of UNS S31803 duplex stainless steels was studied by means of electrochemical anodic polarization, electrochemical impedance spectroscopy, optical microscope, scanning electron microscopy, energy dispersive spectrometer analysis and inclusion statistical analysis. The results show that the addition of rare earth can improve the pitting potential and passive film resistance of the experimental steel. The pitting potential of the steel without RE and with RE are 726 mV and 1019 mV respectively, and the passive film resistance is 26590 Ω·cm^(2) and 67170 Ω·cm^(2) respectively. Rare earth can improve the pitting corrosion resistance of the steel by reducing the number and size of inclusions in the steel and forming stable rare earth oxides dispersed in the steel. Compared with the steel without RE, the number of inclusions in the steel with RE is reduced by 25.93%, the percentage of inclusions with diameter of 0-3 μm increases by 21.57%, and the percentage of inclusions with diameter of 3-5 μm, 5-7 μm and above 7 μm decreases by 15.99%, 5.59% and 4.99%, respectively. After adding rare earth, the oxide inclusions containing Cr, Al, Mn and Ti in the experimental steel are modified into rare earth oxides. The pitting corrosion of the steel without rare earth occurs at the micro crack connecting the oxide inclusion and the matrix, and propagates to the oxide inclusion. However, the pitting corrosion of the steel with rare earth occurs at the micro crack between the rare earth oxide inclusion and the matrix, and propagates to the matrix. Based on this, the schematic diagram of effect of inclusions on the initiation and propagation of pitting corrosion in corrosion micro area of duplex stainless steel is drawn.

关 键 词：双相不锈钢 稀土 点蚀 稀土氧化物 

分 类 号：TG142.7[一般工业技术—材料科学与工程]