热老化对核电阀杆用17-4PH钢电化学腐蚀性能的影响  

Effect of Thermal Aging on Electrochemical Corrosion Properties of 17-4PH Steel for Nuclear Power Valve Stem

作　　者：张磊 王正品[1] 要玉宏[1] 金耀华[1] 史芳杰[2] 黄飞 ZHANG Lei;WANG Zhengpin;YAO Yuhong;JIN Yaohua;SHI Fangjie;HUANG Fei(School of Materials and Chemical Engineering,Xi'an Technological University,Xi'an 710021,China;Suzhou Nuclear Power Research Institute,Suzhou 215004,China)

机构地区：[1]西安工业大学材料与化工学院,陕西西安710021 [2]苏州热工研究院有限公司,江苏苏州215004

出　　处：《热加工工艺》2020年第2期108-113,共6页Hot Working Technology

基　　金：国家自然科学基金项目(51371132);陕西省光电功能材料与器件重点实验室开放基金项目(2015SZSj-59-7).

摘　　要：为了研究热老化时长对核电阀杆用17-4PH不锈钢电化学腐蚀性能的影响,在温度350℃、压力16.5 MPa下对17-4PH钢开展加速热老化试验,采用PARSTAT 2273电化学工作站和扫描电镜(SEM)研究了经不同时长热老化17-4PH钢在0.6M氯化钠溶液中的电化学腐蚀性能。结果表明,随热老化时间的延长,17-4PH钢的开路电位OCP、自腐蚀电位Ecorr和点蚀电位准b负移,自腐蚀电流Icorr和钝化电流Ip增大,电荷转移电阻Rct减小,双电层电容Cdl增大。经不同时长热老化后,17-4PH钢在0.6 M氯化钠溶液中的表面活性增加,钝化膜溶解速率增加,腐蚀反应阻力减小,耐腐蚀性能降低。SEM结果表明,不锈钢中的第二相不仅会导致不锈钢内部形成腐蚀微电池,加速腐蚀速率,还破坏了不锈钢表面钝化膜的完整性,导致不锈钢耐腐蚀性能下降。In order to study the effect of thermal aging time on electrochemical corrosion properties of 17-4 PH stainless steel for nuclear power valve stem,accelerated thermal aging test of 17-4 PH steel was carried out at temperature of 350℃and pressure of 16.5 MPa.The electrochemical corrosion performance of 17-4 PH steel in 0.6 M NaCl solution was studied by using the PARSTAT 2273 electrochemical workstation and SEM.The results show that the open circuit potential OCP,self corrosion potential Ecorr and pitting corrosion potentialφb of 17-4 PH steel negatively shift with the prolongation of thermal aging time.The self-corrosion current Icorr and passivation current Ip increase.The charge transfer resistance Rctdecreases and the double-layer capacitance Cd lincreases.The surface activity of 17-4 PH steel in 0.6 M NaCl solution after long thermal aging increases,the dissolution rate of passivation film increases,the corrosion reaction resistance decreases and the corrosion resistance decreases.The SEM results show that the second phase of stainless steel not only leads to the formation of corrosion microcells in stainless steel,accelerate the corrosion rate,but also destroys the integrity of passivation film on the surface of stainless steel,resulting in the decrease of corrosion resistance of stainless steel.

关 键 词：17-4PH不锈钢 热老化 电化学 腐蚀性能 

分 类 号：TM623[电气工程—电力系统及自动化] TG142.71[一般工业技术—材料科学与工程]