李楠,洪悦,伍翠兰,徐强.低碳钢气体氮碳共渗及后续淬火研究[J].表面技术,2018,47(11):9-16.
LI Nan,HONG Yue,WU Cui-lan,XU Qiang.Gaseous Nitrocarburizing and Post-quenching of Low Carbon Steel[J].Surface Technology,2018,47(11):9-16 |
| 低碳钢气体氮碳共渗及后续淬火研究 |
| Gaseous Nitrocarburizing and Post-quenching of Low Carbon Steel |
| 投稿时间：2018-08-27 修订日期：2018-11-20 |
| DOI：10.16490/j.cnki.issn.1001-3660.2018.11.002 |
| 中文关键词: 氮碳共渗 淬火 化合物层 复合强化层 马氏体 奥氏体 |
| 英文关键词:nitrocarburizing quench compound layer multiphase strengthened layer martensite austenite |
| 基金项目:国家自然科学基金（51071064，11427806） |
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| Author | Institution |
| LI Nan | School of Material Science and Engineering, Hunan University, Changsha 410082, China |
| HONG Yue | School of Material Science and Engineering, Hunan University, Changsha 410082, China |
| WU Cui-lan | School of Material Science and Engineering, Hunan University, Changsha 410082, China |
| XU Qiang | School of Material Science and Engineering, Hunan University, Changsha 410082, China |
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| 中文摘要: |
| 目的 减少传统氮碳共渗及后续淬火形成的马氏体层中大量孔洞及其性能差的缺陷，寻求优化的工艺参数，在低碳钢表面获得少孔、高强、高韧的强化层。方法 采用X射线衍射、扫描电镜、透射电镜及显微硬度计对不同工艺参数条件下制备的强化层的微观组织结构和性能进行表征。结果 氮碳共渗化合物层经850 ℃加热油淬后转变成多孔马氏体，降低淬火温度、缩短共渗时间、减少共渗气氛中的NH3流量、增加CO流量均可减少淬火试样表面孔洞的数量。经680 ℃加热淬火后，氮碳共渗化合物层转变成马氏体加残余奥氏体的复相强化层，这种复相强化层的硬度可达到1000HV，且具有很好的韧性。经过120 ℃低温回火后，复相强化层仍保持高硬度和良好韧性。相对于增加CO流量而言，降低NH3流量不仅能减少表面的孔洞，也可保持680 ℃淬火强化层的高硬度和良好韧性，同时也可缩短氮碳共渗时间，节约成本。结论 优化的氮碳共渗淬火工艺能获得由马氏体和奥氏体组成的复相强化层，并显著减少表面孔洞。强化层中广泛分布的奥氏体能显著改善复相强化层的韧性。因此，复相强化层具有高强高韧且少孔的优点。 |
| 英文摘要: |
| The work aims to decrease the shortcomings of numerous pores and poor performance in the martensitic layers fabricated by traditional nitrocarburizing and post-quenching and find out the optimized process parameters to obtain a streng?thened layer with few pore, high strength and high tenacity on low carbon steel. X-ray diffraction (XRD), scanning elec??tron mi?cr?oscopy (SEM), transmission electron microscopy (TEM) and microhardness tester were used to characterize the microstruc?tures and the properties of the strengthened layers formed at different process parameters. Nitrocarburized compound layer was transformed into a porous martensitic layer after re-heating and oil-quenching at 850 ℃. The quantity of pores on the surface quenched specimen could be decreased by lowering quenching temperature, reducing nitrocarburizing time, decreasing gas fluxes of NH3 and increasing the gas fluxes of CO. After post-quenching at 680 ℃, the nitrocarburized compound layer could be transformed into a multiphase strengthened layer composed of martensite and retained austenite. The multiphase strengthened layer had the hardness up to 1000HV and good toughness. Even after tempering at 120 ℃, the multiphase strengthened layer could still keep the high hardness and good toughness. Compared with increasing of the gas fluxes of CO during the nitrocar???burizing process, decreasing of gas fluxes of NH3 not only decreased the pores and kept high hardness and good toughness of the strengthened layers, but also reduced the nitrocarburizing time and costing. The optimized nitrocarburizing and post-quenching process can be used to fabricate a multiphase strengthened layer composed of martensite and retained austenite and reduce the surface pores. The widely distributed austenite-blocks in the strengthened layers can greatly improve the toughness. Therefore, the multiphase strengthened layer has advantages of high hardness, high toughness and few pores. |
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