预渗氮处理对20CrMnTi钢真空渗碳层耐蚀性能的影响  

Effect of pre-nitriding on corrosion resistance of 20CrMnTi steel vacuum carburized layer

作　　者：李卓程 田勇[1] 王斌[1] 王昊杰 Li Zhuocheng;Tian Yong;Wang Bin;Wang Haojie(State Key Laboratory of Rolling and Automation,Northeastern University,Shenyang Liaoning 110819,China;School of Mechanical Engineering,Shenyang University of Technology,Shenyang Liaoning 110870,China)

机构地区：[1]东北大学轧制技术及连轧自动化国家重点实验室,辽宁沈阳110819 [2]沈阳工业大学机械工程学院,辽宁沈阳110870

出　　处：《金属热处理》2022年第10期211-217,共7页Heat Treatment of Metals

基　　金：辽宁省自然科学基金(2020-MS-078);辽宁省“兴辽英才计划”(XLYC2007018)。

摘　　要：在真空渗碳前预先对20CrMnTi钢进行真空渗氮处理,采用OM、SEM和XRD研究了预渗氮处理对渗碳层显微组织及腐蚀形貌的影响,通过电化学测试和浸泡腐蚀质量损失来评价其耐蚀性能。结果表明,经过预渗氮处理的渗碳试样的渗层马氏体更加细小并且有大量渗碳体析出,耐腐蚀性明显提高,自腐蚀电流密度从1.3608×10^(-5)mA·cm^(-2)下降到2.9817×10^(-5)mA·cm^(-2),自腐蚀电位由-0.7741 V提高到了-0.6672 V,其腐蚀速率和发生腐蚀的倾向大大降低,并且由质量损失得出的腐蚀速率仅为渗碳试样的一半。这主要是由于预渗氮+渗碳处理试样渗层细小的马氏体组织和渗碳体在腐蚀时会阻碍孔蚀的扩展从而降低腐蚀速率,并且渗层的氮原子会与溶液发生化学反应生成NH~+及NO~-或NO~-,降低Cl~-对材料的腐蚀作用。20 CrMnTi steel was pre-nitrided before vacuum carburizing, and the effect of pre-nitriding treatment on microstructure of the carburized layer and the morphology of the corroded surface was investigated by means of OM, SEM and XRD, and the corrosion resistance was evaluated by electrochemical tests and corrosion rate calculated by mass loss. The results show that the martensite of the carburized layer of the pre-nitrided and carburized specimen is finer with a large amount of cementite precipitates, and the corrosion resistance is significantly improved. The corrosion rate and the tendency of corrosion to occur are greatly reduced, the self-corrosion current density is reduced from 1.3608×10^(-5)mA·cm^(-2)to 2.9817×10^(-5)mA·cm^(-2)and the self-corrosion potential is increased from-0.7741 V to-0.6672 V, the corrosion rate calculated by mass loss is only half of that of the carburized specimen. This is mainly due to the finer martensite and cementite of the pre-nitrided and carburized specimen hindering the expansion of pitting and thus reduce the corrosion rate, and the nitrogen atoms in carburized layer will react chemically with the solution to generate NHand NOor NO, which will reduce the corrosion effect of Cl.

关 键 词：20CRMNTI钢 预渗氮 真空渗碳 显微组织 耐蚀性 孔蚀 

分 类 号：TG156.8[金属学及工艺—热处理]