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本文用光学显微镜、透射电镜、电子探针分析和X—射线衍射及化学相分析等方法对18CrMnNiMoA钢气体碳氮共渗渗层的组织结构、合金元素分布及残余应力和残余奥氏体在渗层中的分布规律进行了较为系统的研究。结果表明,在共渗过程中合金元素Cr、Mn、Ni、Mo均在表面有富集,其富集区与残余拉应力峰值及残余奥氏体量峰值相对应,而残余奥氏体分布又影响渗层硬度的分布。渗层中碳、氮化物有:M_3(CN)、CrN、Cr_7C_3、Mo_2C、γ-Fe_4N、Mn_4N、AlN、M_(23)C_6及了iN、碳、氮化物的形成使基体中化合物形成元素贫化。在渗层中碳化物层及粗大马氏体层间均有板条马氏体存在,但主要是片状马氏体。同时,结合试验结果对渗层的组织结构及碳、氮化物形成机制进行了探讨。
In this paper, microstructure, elemental distribution, residual stress and retained austenite in 18CrMnNiMoA steel were investigated by optical microscope, transmission electron microscopy, electron probe analysis, X-ray diffraction and chemical phase analysis. Layer in the distribution of a more systematic study. The results show that alloying elements Cr, Mn, Ni and Mo are enriched on the surface during the process of infiltration. The enrichment zone corresponds to the peak value of residual tensile stress and the peak value of retained austenite, while the residual austenite distribution Affect the hardness of the distribution layer. The formation of carbon and nitrogen nitrides in the infiltrated layer includes: M_3 (CN), CrN, Cr_7C_3, Mo_2C, γ-Fe_4N, Mn_4N, AlN and M_ (23) C_6, The There are lath martensite in the carburized layer and coarse martensite in the infiltrated layer, but mainly lamellar martensite. At the same time, combined with the experimental results on the infiltration layer structure and carbon and nitride formation mechanism were discussed.