42CrMo4钢硼氮离子复合渗与离子渗氮对比研究

Comparative Study on Plasma Boron-Nitriding and Plasma Nitriding for 42CrMo4 Steel

目的为了进一步提高42CrMo4钢离子渗氮层的硬度,研发硼氮离子复合渗创新技术,并与离子渗氮层特性进行对比研究。方法在520℃、6 h的相同工艺条件下,对42CrMo4钢分别进行硼氮离子复合渗和离子渗氮处理。利用光学显微镜、XRD、显微硬度计、摩擦磨损测试机和电化学工作站对截面显微组织、物相、截面硬度、耐磨性和耐蚀性进行测试和分析。结果硼氮离子复合渗可显著提高渗氮效率,在520℃、6 h工艺条件下,化合物层厚度由18.78μm增加到29.44μm,有效硬化层厚度由265μm增加到355μm。同时,硼氮离子复合渗后在渗层形成了硼铁化合物FeB和Fe_(2)B,显著提高了渗层的硬度和耐磨性;表面硬度由750HV0.05提高至1002HV0.05,耐磨性和耐蚀性明显提高,磨损率由3.06 mg/cm^(2)下降到1.02 mg/cm^(2);自腐蚀电位由–648.89 mV提高至–494.32 mV。结论与离子渗氮相比,硼氮离子复合渗具有显著优势,不仅可以提高离子渗效率,还可显著提升渗层性能,包括渗层硬度、耐磨性和耐蚀性。

The work aims to develop plasma boron-nitriding(PNB)technology to further improve the hardness of 42CrMo4 steel nitriding layer and comparatively study the properties of plasma nitriding layer.Under the same technological conditions of 520℃and 6 h,42CrMo4 steel was treated by plasma boron-nitriding and plasma nitriding,respectively.The cross-sectional microstructures,phase compositions,cross-sectional hardness,wear and corrosion resistance of the nitriding layer was tested and analyzed by optical microscope,XRD,microhardness tester and wear tester and electrochemical workstation.PNB significantly increased the nitriding efficiency.Under the technological conditions of 520℃and 6 h,the thickness of compound layer and effective hardening layer increased from 18.78μm to 29.44μm,and 265μm to 355μm,respectively.Meanwhile,FeB and Fe_(2)B were formed in the surface layer after plasma boron-nitriding,which significantly improved the hardness and wear resistance of nitriding layer.The surface hardness increased from 750HV0.05 to 1002HV0.05,and both wear and corrosion resistance were obviously enhanced.The wear rate was decreased from 3.06 mg/cm^(2) to 1.02 mg/cm^(2),and the self-corrosion potential was increased from–648.89 mV to–494.32 mV.Compared with plasma nitriding,plasma boronnitriding has obvious advantages,which can not only improve the efficiency of plasma nitriding,but also significantly improve the properties of the nitriding layer,including hardness,wear resistance and corrosion resistance.