耐磨耐蚀Fe基激光熔覆层的组织和性能研究

Microstructure and Properties of Wear and Corrosion Resistant Fe-based Laser Cladding Layer

目的采用同步送粉激光熔覆技术制备兼具耐磨与耐蚀性能的Fe基熔覆层,获取熔覆层的物相组织、硬度与耐蚀性,并研究热处理对熔覆层性能的影响。方法采用Fe-B-C-Cr-Ni-Mo-Nb-V多组元合金粉末,在304不锈钢基体上制备Fe基耐磨耐蚀熔覆层,并模拟淬火加高温回火的热处理工艺,进行熔覆层热处理试验。采用XRD、SEM表征熔覆层的物相组成和微观组织,采用显微硬度计测试熔覆层的硬度,通过极化曲线和阻抗谱对熔覆层的电化学腐蚀性能进行测试。结果所制备的激光熔覆层同基体具有良好的冶金结合,熔覆层物相包含奥氏体γ相、马氏体α'相和Cr23(C,B)6相。熔覆层的微观组织为亚共晶结构,由尺寸细小的树枝晶和枝晶间层片状共晶组织构成,热处理后还形成了大量微纳尺度的析出相。激光熔覆层的硬度相对于基体硬度提高了2.5~2.7倍,热处理后试样最高硬度达521.4HV。激光熔覆层的自腐蚀电位为−0.428 V,腐蚀电流密度为1.41×10^(−5) A/cm^(2),热处理后的熔覆层自腐蚀电位降低,腐蚀电流密度增大,阻抗值明显减小,耐蚀性降低。结论利用激光熔覆Fe-B-C-Cr-Ni-Mo-Nb-V多组元合金粉末可制备致密、无缺陷的Fe基熔覆层,细晶强化以及大量硬质共晶组织的存在使熔覆层的硬度得到显著提升。高Cr、Ni含量保证了熔覆层具有良好的耐蚀能力,淬火加高温回火的热处理工艺使熔覆层的硬度提升,但耐蚀能力有一定程度的下降。该Fe基熔覆层在耐磨耐蚀涂层技术领域具有较好的应用前景。

The work aims to use synchronous powder feeding laser cladding technology to prepare a Fe-based cladding layer with both wear resistance and corrosion resistance,and to obtain the phase constituent,microstructure,hardness,and cor-rosion resistance of the cladding layer,as well as to study the effect of heat treatment on the properties of the cladding layer.Fe-B-C-Cr-Ni-Mo-Nb-V multi-component alloy powder was used to prepare the Fe-based wear and corrosion resistant cladding layer on the stainless steel substrate.Heat treatment was conducted on the cladding layer to simulate quenching and high-temperature tempering processes.XRD and SEM were used to characterize the phase constituent and microstructure of the cladding layer.Microhardness tests were performed by a microhardness tester.Polarization curves and impedance spectra were used to test the electrochemical corrosion performance of the cladding layer.The laser cladding layer exhibited good metallur-gical bonding with the substrate.The phase constituent of the cladding layer included austeniteγphase,martensiteα'phase,and Cr23(C,B)6 phase.Microstructure of the cladding layer consisted of eutectic structure composed of fine dendrite and interden-dritic lamellar eutectic.After heat treatment,a larger number of micro/nano-scale precipitates were formed.The hardness of the laser cladding layer increased by 2.5-2.7 times compared to that of the substrate,reaching a maximum hardness of 521.4HV af-ter heat treatment.The corrosion potential of the laser cladding layer was−0.428 V,and the corrosion current density was 1.41×10^(−5)A/cm^(2).After heat treatment,the cladding layer exhibited a lower corrosion potential,higher corrosion current density,and significantly reduced impedance,indicating decreased corrosion resistance.Fe-B-C-Cr-Ni-Mo-Nb-V multi-component alloy powders can be used to prepare dense and defect-free Fe-based cladding layer.The hardness of the cladding layer is significantly improved due to the presence of fine grain strengthening and a large amount of hard eutectic structure.The high Cr and Ni con-tents ensure good corrosion resistance of the cladding layer.Quenching and high-temperature tempering heat treatment process can further enhance the hardness of the cladding layer,but lead to a reduction in corrosion resistance.The Fe-based cladding layer has promising applications in the field of wear and corrosion resistant coating technology.