2Cr13不锈钢活性屏等离子体源渗氮层组织与耐蚀性能  

Microstructure and Corrosion Resistance of Nitrided Layer on 2Cr13 Stainless Steel by Active Screen Plasma Source Nitriding

作　　者：李广宇[1] 李刚 雷明凯[2] LI Guang-yu;LI Gang;LEI Ming-kai(Yingkou Institute of Technology,Liaoning Yingkou 115014,China;Dalian University of Technology,Liaoning Dalian 116024,China)

机构地区：[1]营口理工学院,辽宁营口115014 [2]大连理工大学,辽宁大连116024

出　　处：《表面技术》2022年第6期300-306,共7页Surface Technology

基　　金：辽宁省教育厅科学研究经费项目(L2019004);营口市企业博士双创计划项目(QB-2019-06)。

摘　　要：目的探讨活性屏等离子体源渗氮技术提高马氏体不锈钢硬度与耐蚀性能的可行性。方法将2Cr13马氏体不锈钢进行350~550℃、6 h活性屏等离子体源渗氮处理,采用光学显微镜(OM)、电子探针显微分析仪(EPMA)和X射线衍射仪(XRD)分析渗氮层的组织、成分和相结构,使用显微硬度计测试渗氮层的显微硬度,利用电化学腐蚀试验解析评估渗氮层的耐蚀性能。结果经活性屏等离子体源渗氮处理后,可在马氏体不锈钢表面形成厚度为2~45μm,N原子分数为20%~25%的渗氮层,其表面显微硬度达1050~1350 HV0.25,是基体硬度的4~5倍。350℃时,渗氮层以ε-Fe_(2-3)N相为主,且含有少量αN相;450℃时,渗氮层由αN、ε-Fe_(2-3)N和γ’-Fe_(4)N相构成;渗氮温度升至550℃时,渗氮层由α-Fe、CrN和γ’-Fe_(4)N相构成,αN、ε-Fe^(2-3)N相消失。350、450℃时,渗氮层在3.5%NaCl溶液中的阳极极化曲线出现明显钝化区,而未渗氮的2Cr13不锈钢并未发现钝化区,自腐蚀电位E_(corr)由未渗氮的–308 mV(vs.SCE)分别升高至–151、–104 mV,腐蚀电流密度Jp均维持在0.03~0.2μA/cm^(2)内。550℃时,渗氮层表面因CrN相析出,耐蚀性能相对恶化。电化学阻抗谱结果显示,350、450℃时,渗氮层表面钝化膜电荷转移电阻Rct由未渗氮的5.25×10^(4)Ω·cm^(2)分别增至2.76×10^(5)、3.18×10^(5)Ω·cm^(2),双电层电容Cdl由未渗氮的473μF/cm^(2)分别降至74、103μF/cm^(2),说明渗氮层表面形成的钝化膜更厚,致密性更好,能有效阻碍反应离子的渗透和迁移,耐蚀性能显著提高。结论活性屏等离子体源渗氮技术处理2Cr13马氏体不锈钢可以获得高的表面硬度和优异的耐腐蚀性能。This paper aims to explore the feasibility of the active screen plasma source nitriding technology to improved the hardness and corrosion resistance of martensite stainless steel.The 2Cr13 martensitic stainless steel was nitrided by the active screen plasma source nitriding at 350~550℃for 6 h.The microstructure,phase structure and microhardness of the nitrided layer were characterized by means of optical microscopy(OM),electron probe microanalyzer(EPMA),X-ray diffraction(XRD)and microhardness tester.The corrosion resistance of the nitrided layer were evaluated by electrochemical corrosion test.The results show that after nitriding treatment with active screen plasma source nitriding,the nitrided layer with a thickness range of 2~45μm and N concentration of 20at.%~25at.%(atomic fraction)can be obtained on the surface of martensitic stainless steel,and its surface microhardness was measured to be 1050~1350HV0.25,which is about 4~5 times of the untreated substrate.The nitrided layer was mainly consisted of ε-Fe_(2-3)N phases and a few αN phase at 350℃.The nitrided layer consisted of αN,ε-Fe_(2-3)N and γ’-Fe_(4)N phase at 450℃.When the nitriding temperature increases to 550℃,the nitrided layer mainly consists of α-Fe,CrN and γ’-Fe_(4)N phases,as well as αN and ε-Fe_(2-3)N phases disappeared nearly.The anodic polarization curves of the nitrided layer at nitriding temperature of 350℃and 450℃in 3.5%NaCl solution showed an obvious passivation region,but no passivation region is found in the unnitrided 2Cr13 stainless steel.The self-corrosion potential Ecorr increases from-308 mV(vs.SCE)without nitriding to-151 mV and-104 mV,respectively,and the corrosion current density remain in the lower range of 0.03~0.2μA/cm^(2).However,the corrosion resistance is relatively deteriorated due to the CrN phase precipitation on the surface of the nitrided layer at 550℃.The EIS results show that the interfacial charge transfer resistance Rct of the nitrided layer passive film at 350℃and 450℃increases from

关 键 词：活性屏等离子体源渗氮 马氏体不锈钢 渗氮层 相结构 硬度 耐蚀性能 

分 类 号：TG156.8[金属学及工艺—热处理] TG142.1[金属学及工艺—金属学]