TiN夹杂物对超纯铁素体不锈钢点蚀的影响  

Effect of TiN Inclusion on Pitting of an Ultra-Pure Ferritic Stainless Steel

作　　者：南海[1] NAN Hai(State Key Laboratory of Advanced Stainless Steel Materials,Taiyuan Iron and Steel(Group)Co.,Ltd.,Taiyuan 030003,China)

机构地区：[1]太原钢铁(集团)有限公司先进不锈钢材料国家重点实验室,太原030003

出　　处：《腐蚀与防护》2021年第9期22-27,43,共7页Corrosion & Protection

基　　金：山西省科技重大专项(20191102006);山西省科技计划揭榜招标项目(20201101011)。

摘　　要：通过电化学试验和浸泡试验,利用扫描电镜(SEM)、透射电镜(TEM)和原子力显微镜(AFM)表征了超纯铁素体不锈钢的点蚀坑尺寸、TiN夹杂物的微观结构以及TiN与基体的电势差和高度差,分析了TiN对试样点蚀发生和扩展的作用机理。结果表明:试样的腐蚀电位和点蚀电位分别为94 mV和353 mV,点蚀坑的平均宽度和深度分别为203.6μm和114.74μm, TiN夹杂物以单个或团簇的形式存在;TiN比基体的电势高65 mV,点蚀优先在TiN与基体界面处发生,基体成为阳极发生微电偶腐蚀;由"孔内活化-孔外钝化"腐蚀电池引起的自催化过程加速了点蚀的扩展。Through electrochemical test and immersion test, using scanning electron microsopy(SEM), transmission electron microscope(TEM) and atomic force microscope(AFM) to characterize the size of pitting pits, the micro morphology of TiN inclusion, and the potential difference and height difference between TiN and substrate of an ultra-pure ferritic stainless steel. And the mechanism of TiN on the occurrence and expansion of pitting corrosion of the sample was analyzed. The results showed that corrosion potential and pitting potential of the sample were 94 mV and 353 mV, respectively. The average width and depth of pitting pits were 203.6 μm and 114.74 μm, respectively. TiN inclusion existed in the form of single or cluster. The potential of TiN was 65 mV higher than that of the substrate. The pitting corrosion occurred preferentially at the interface between TiN and substrate, and the substrate became the anode for micro galvanic corrosion. The autocatalytic process caused by "activation in the hole-passivation out of the hole" accelerated the expansion of pitting corrosion.

关 键 词：超纯铁素体不锈钢 TIN 电势差 点蚀 

分 类 号：TG172[金属学及工艺—金属表面处理]