FeCrNiMo激光熔覆层组织与电化学腐蚀行为研究  

Microstructure and Electrochemical Corrosion Behavior of FeCrNiMo Layer Fabricated by Laser Cladding

作　　者：黄杰 贺定勇[1] 杜开平 杨延格[3] 郭星晔 吴旭[1] 于月光 周正[1] HUANG Jie;HE Ding-yong;DU Kai-ping;YANG Yan-ge;GUO Xing-ye;WU Xu;YU Yue-guang;ZHOU Zheng(Faculty of Materials and Manufacturing,Beijing University of Technology,Beijing 100124,China;BGRIMM Technology Group,Beijing 100160,China;Institute of Metal Research,Chinese Academy of Sciences,Shenyang 110016,China)

机构地区：[1]北京工业大学材料与制造学部,北京100124 [2]矿冶科技集团有限公司,北京100160 [3]中国科学院金属研究所,沈阳110016

出　　处：《表面技术》2020年第12期228-234,共7页Surface Technology

基　　金：国家重点研发计划项目(2017YFB0306100)。

摘　　要：目的研究所设计FeCrNiMo激光熔覆层的组织结构及电化学腐蚀行为,用于解决液压支架表面防护与修复问题。方法采用激光熔覆技术在27SiMn钢表面制备FeCrNiMo合金熔覆层,通过XRD、光学显微镜和SEM表征其微观组织结构,利用动电位极化与交流阻抗谱技术研究熔覆层电化学腐蚀行为。结果在适宜工艺条件下实现了单道熔覆层厚度达2 mm以上,且无明显气孔、裂纹等缺陷。熔覆层具有胞状枝晶组织特征,枝晶内为马氏体,晶间富Cr、Mo的铁素体有效缓解了马氏体相变的高应力,达到了较好的强韧化匹配。熔覆层在3.5%NaCl和0.5 mol/L H2SO4溶液中均呈现出明显的钝化行为,钝化区间宽度分别为300 mV和1310 mV,自腐蚀电位分别为–140.2 mV和2.3 mV,自腐蚀电流密度分别为5.0×10–8A/cm2和1.3×10–3A/cm2,极化电阻分别为3.5×105?·cm2和6261.4?·cm2,具有较为优异的耐腐蚀性能,且显著优于基体材料,但其双相组织特征易导致微区发生选择性腐蚀。结论所设计的FeCrNiMo合金及相应激光熔覆工艺,满足实际工程对于熔覆层高效制备、成形质量及耐蚀性的要求,可用于液压支架表面防护与修复。The work aims to study the microstructure and electrochemical corrosion behavior of FeCrNiMo laser cladding layer,so as to solve the problems of hydraulic support surface protection and repair.FeNiCrMo alloy layer was prepared on 27 SiMn steel substrate by laser cladding,and the microstructure and electrochemical corrosion behavior of this layer were investigated by XRD,optical microscope,SEM,potentiodynamic polarization and electrochemical impedance spectroscopy.Under optimized processing parameters,the layer had a single-cladding thickness of over 2 mm,without obvious defects like pores,cracks.The cladding layer presented a cellular dendritic structure involving martensite in dendrite and intergranular Cr/Mo-rich ferrite,thus achieving a good balance of strengthening and toughening.The cladding layer exhibited obvious passivation behavior in both 3.5 wt%NaCl and 0.5 mol/L H2SO4 solutions.The passive region had a width of 300 mV and 1310 mV,the corrosion potential was detected to be–140.2 mV and 2.3 mV,the corrosion current density was measured as 5.0×10–8 A/cm2 and 1.3×10–3 A/cm2,and the polarization resistance was calculated to be 3.5×105?·cm2 and 6261.4?·cm2,respectively.This cladding layer depicted excellent corrosion resistance that was superior to the substrate,although selective corrosion occurred in micro-area due to duplex phase structure.Therefore,the designed FeNiCrMo alloy and related laser cladding parameters satisfy the engineering demands for processing efficiency and performance and can be used for protecting and repairing hydraulic supports.

关 键 词：激光熔覆 FeCrNiMo合金 微观组织 动电位极化 交流阻抗谱 

分 类 号：TG172[金属学及工艺—金属表面处理]