冯治国,赵驯峰,刘静.电磁感应真空变脉冲工艺对20CrMnTi钢渗碳层组织与性能的影响[J].表面技术,2018,47(12):76-82.
FENG Zhi-guo,ZHAO Xun-feng,LIU Jing.Effects of Electromagnetic Induction Vacuum Transform-pulse on Carburizing Structure and Performance of 20CrMnTi Steel[J].Surface Technology,2018,47(12):76-82 |
| 电磁感应真空变脉冲工艺对20CrMnTi钢渗碳层组织与性能的影响 |
| Effects of Electromagnetic Induction Vacuum Transform-pulse on Carburizing Structure and Performance of 20CrMnTi Steel |
| 投稿时间：2018-07-25 修订日期：2018-12-20 |
| DOI：10.16490/j.cnki.issn.1001-3660.2018.12.011 |
| 中文关键词: 电磁感应 真空渗碳 变脉冲 强渗-扩散 EBSD 微观组织 |
| 英文关键词:electromagnetic induction vacuum carburizing transform-pulse boost-diffusion EBSD microstructure |
| 基金项目:国家自然科学基金资助项目（51574096，51464008）；贵州省优秀青年科技人才培养项目（黔科合平台人才[2016]5607号，黔科合JZ字[2014]2003号） |
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| 中文摘要: |
| 目的 研究真空脉冲渗碳过程中“强渗”与“扩散”脉冲分布占比对20CrMnTi钢渗碳层晶粒粗化行为及组织性能的影响。方法 采用一种电磁感应真空变脉冲渗碳新方法，经“原脉冲”、“变强渗”、“变扩散”、“变压力”四种工艺，制备了组织致密的20CrMnTi钢渗碳层。利用SEM、EBSD、自动显微硬度仪以及XRD应力衍射仪等对渗碳层的微观形貌、晶体相变特征、硬度梯度以及表面残余应力进行了深入分析。结果 对比分析四种工艺方法，“变强渗”工艺虽使20CrMnTi钢渗碳层厚度达到1450 μm，但渗碳层中仍存在大量块状Fe3C；“变扩散”工艺使20CrMnTi钢渗碳层的Fe3C含量下降到3.88%，残余奥氏体含量下降到7.32%，厚度达到1320 μm，其中表层0~60 μm范围内，硬度提高到780 HV0.5，表面残余压应力增加到-231 MPa。故“变扩散”工艺使渗碳层组织性能最佳。结论 “变强渗”工艺增加了渗碳前期表层与内部的碳浓度差，提高了碳原子扩散驱动力，利于渗碳层生长；“变扩散”工艺在渗碳后期使碳化物进一步溶解，这利于碳原子向渗碳层内部充分扩散，降低了渗碳层的碳化物析出和残余奥氏体形成。 |
| 英文摘要: |
| The work aims to study grain coarsening behavior and microstructure on the carburized layer of 20CrMnTi steel by controlling the distribution of “boost” and “diffusion” pulses in the process of vacuum pulse carburizing. An electromagnetic induction vacuum pulse carburizing was used to prepare carburized layers on 20CrMnTi steel through four processes of “original pulse”, “variable boost”, “variable diffusion” and “variable pressure” respectively. Meanwhile, the microstructure, crystal phase transition, hardness gradient and surface residual stress of the carburized layers were analyzed deeply through SEM, EBSD, automatic microhardness tester and XRD residual stress tester. Through the comparison and analysis of four processes, the thickness of the carburized layer of 20CrMnTi steel reached 1450 μm, but there was still a large amount of massive Fe3C in the carburized layer after the process of “variable boost”. The Fe3C, the retained austenite and the thickness in carburized layer of 20CrMnTi steel treated by the “variable diffusion” process decreased to 3.88%, 7.32% and 1320 μm respectively. In addition, the hardness of the carburized layer in the depth of 0 to 60 μm increased to 780 HV0.5 and the surface residual compressive stress increased to -231 MPa. From the results, the “variable diffusion” could provide the optimum structure property. “Variable boost” process increases the carbon concentration difference between the surface layer and the interior during the early stage of carburization and improves the diffusion driving force of carbon atoms, which is favorable for the growth of the carburized layer. Moreover, the “variable diffusion” process further dissolves the carbides in the late stage of carburization, which facilitates the full diffusion of carbon atoms into the interior of the carburized layer and reduces carbide precipitation and formation of residual austenite in the carburized layer. |
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