反应温度及时间对奥氏体不锈钢渗铬层组织结构的影响

Effect of reaction temperature and time on microstructure of chromizing layer on austenitic stainless steel matrix

摘要:

利用固体粉末包埋技术对316H奥氏体不锈钢进行了1090℃保温0.5-15h的和750-1150℃保温10h的化学热处理，研究了不同工艺参数对渗铬层组织结构和耐磨性的影响。通过光学金相显微镜（OM），电子扫描显微镜（SEM），能谱仪（EDS）以及X射线衍射仪（XRD）等分析手段，研究了保温时间和反应温度对渗铬层的微观组织结构的影响规律，使用摩擦磨损试验机研究了不同工艺参数对渗铬层耐磨性的影响。结果表明：反应温度对渗铬层的厚度影响显著，在同一温度下进行渗铬，渗铬层的厚度与渗铬时间呈抛物线关系；渗铬层主要由Cr23C6、Cr2C和α-Fe-Cr固溶体组成，在渗铬过程中，首先在试样表面形成碳铬化物层，随着反应温度提高或保温时间延长，在碳铬化合物层下会生成α-Fe-Cr固溶体层，进一步提高反应温度和保温时间碳铬化合物层逐渐消失。渗铬后试样的耐磨性明显提高，且在相同温度下渗铬，保温时间短的耐磨性好；相同保温时间，反应温度低的耐磨性好。

Abstract:

Using solid powder embedding technique, 316H austenitic stainless steel was subjected to chemical heat treatment at 1090℃ for 0.5-15h and 750-1150℃ for 10h. The effects of different process parameters on the structure and wear resistance of the chromizing layer were studied. Optical metallurgical microscope (OM) , electron scanning microscope (SEM), Energy Dispersive X-Ray Spectroscopy (EDS) and X-ray diffractometer (XRD) and other analytical methods were used to study the influence of holding time and reaction temperature on the microstructure of the chromizing layer. Using friction and wear testing machine to study the influence of different technological parameters on the wear resistance of chromizing layer. The results show that the reaction temperature has a significant effect on the thickness of the chromizing layer. The thickness of the chromizing layer and the chromizing time are parabolic at the same chromizing termprature. The chromizing layer is mainly composed of Cr23C6, Cr2C and α-Fe-Cr solid solution. In the process of chromizing, first form a carbon chromium layer on the surface of the sample. As the reaction temperature increases or the holding time is extended, α-Fe-Cr solid solution layer will be formed under the carbon chromium compound layer, and further increase the reaction temperature and holding time ,the carbon chromium compound layer will gradually disappeare. After chromizing, the wear resistance of the sample is significantly improved. Chromizing at the same temperature, the shorter the holding time of the sample, the better the wear resistance; the same holding time, the lower the reaction temperature of the sample, the better the wear resistance.