摘要
目的通过渗铬处理改善不锈钢表面的耐磨性能和耐腐蚀性能,重点研究不同渗铬温度对渗铬层结构和性能的影响。方法采用固体包埋粉末渗铬法,在850、900、950、1000℃渗铬温度下进行渗铬处理。通过扫描电镜、能谱仪、X射线衍射仪对渗铬层的化学成分、组织结构进行分析,利用显微硬度计、洛氏压痕仪、摩擦磨损试验机和盐雾腐蚀试验机对渗铬层的力学性能和耐腐蚀性能进行表征。结果渗铬层表面分布着不连续的氮化铬凸起晶粒以及在凸起晶粒周围存在大量的孔隙,随着渗铬温度增加凸起晶粒逐渐长大,渗铬层的主要物相为Cr_(23)C_(6)、Cr_(2)C、Cr_(2)N。渗铬层厚度、表面硬度随着渗铬温度的增加逐渐提高,渗铬层厚度在1.77~6.52μm之间,渗铬层表面硬度受载荷和渗铬层厚度影响较大。900℃以下渗铬处理的渗铬层耐磨性能较差;当渗铬温度达到950℃以上时,渗铬层的耐磨性能明显提高,在1000℃渗铬层的磨损率降低至3.85×10^(-6)mm^(3)/(N·m)。900℃和950℃渗铬层由于适当的渗铬层厚度和良好的渗层致密性,盐雾腐蚀2016 h后渗铬层仍未发生腐蚀,大幅度提高了不锈钢的耐腐蚀性能。结论950℃渗铬温度下渗铬层具有合适的厚度、良好的渗层致密性和力学性能,大幅度提高了不锈钢表面的耐磨性能和耐腐蚀性能。
The work aims to enhance the wear resistance and corrosion resistance of stainless steel through the solid powder pack chromizing method.Specifically,the effects of different chromizing temperatures(850℃,900℃,950℃,1000℃)on the microstructure and properties of the chromized layers were investigated.The chemical composition and microstructure of the chromized layers were analyzed with scanning electron microscopy(SEM),energy-dispersive X-ray spectroscopy(EDS),and X-ray diffraction(XRD).The experimental results revealed that the chromized layer surface was characterized by a discontinuous distribution of protruding chromium nitride grains which were surrounded by numerous pores.As the chromizing temperature increased,both the size of the protruding grains and the adjacent pores gradually expanded.XRD analysis indicated that the primary phases present in the chromized layer were Cr_(23)C_(6),Cr_(2)C,and Cr_(2)N.These phases were beneficial to enhance the overall mechanical properties of the chromized layers.Increasing the chromizing temperature had a pronounced effect on the thickness of the chromized layer.The thickness of the layer ranged from 1.77μm to 6.52μm.The higher temperature promoted atomic diffusion,which induced the obvious increment of thickness at 1000℃.The microhardness of the chromized layers increased with the increasing the chromizing temperature.In addition,the surface microhardness of the chromized layer was found to be dependent on the applied load.Under an applied load of 25 g,the microhardness of the layers ranged from 449.9HV to 1460.4HV.However,it ranged from 271.2HV to 723.9HV under 100 g applied load.This was attributed to the thin layer thickness and the surface harness was affected by the substrate.Wear resistance tests further demonstrated the temperature-dependent performance of the chromized layer.At chromizing temperatures below 900℃,the wear resistance was relatively poor.However,when the chromizing temperature exceeded 950℃,a remarkable improvement in wear resistance was observed.At a chromizing temperature of 1000℃,the wear rate was reduced to as low as 3.85×10^(‒8) mm^(3)/(N·m).The enhanced wear resistance was linked to both the increased layer thickness and the optimized microstructural characteristics that developed at higher processing temperatures.This significant increase in hardness and wear resistance at high temperature could be attributed to the formation of Cr_(23)C_(6) and Cr_(2)C hard phases in the chromized layers.The neutral salt spray test results showed the great improvement in corrosion resistance by the chromized layers.For the chromized layers at 850℃ and 1000℃,the corrosion pits appeared after 712 h and 430 h tests respectively.No corrosion phenomenon was found on the surface of the chromized layer at 900℃ and 950℃ after 2016 h test.However,corrosion pit appeared on the 304 stainless steel only after 103 h.This outstanding corrosion resistance was primarily due to the compact structure and the optimal thickness of the chromized layer,which together acted as an effective barrier against corrosive agents.In conclusion,this study demonstrates that chromizing at elevated temperatures,especially near 950℃,is an effective method for improving the performance of stainless steel.The optimized chromizing treatment not only increases the hardness and wear resistance,but also significantly enhances the corrosion resistance of the material,thereby extending its service life.These findings provide valuable insights into the surface engineering of stainless steel and suggest that such treatments can play a crucial role in various industrial applications where durability and corrosion resistance are of paramount importance.
作者
袁梦雨
韦春贝
代明江
陈玲
林松盛
石倩
YUAN Mengyu;WEI Chunbei;DAI Mingjiang;CHEN Ling;LIN Songsheng;SHI Qian(School of Materials and Environmental Engineering,Guangxi Minzu University,Nanning 530000,China;Guangdong Provincial Key Laboratory of Modern Surface Engineering Technology,National Engineering Laboratory of Modern Materials Surface Engineering Technology,Institute of New Materials,Guangdong Academy of Sciences,Guangzhou 510651,China)
出处
《表面技术》
北大核心
2025年第17期202-211,共10页
Surface Technology
基金
广东省基础与应用基础研究基金项目(2022A1515240048)
广东省科技计划项目(2023B1212060045)。
关键词
渗铬温度
硬度
摩擦磨损
盐雾腐蚀
chromizing temperature
hardness
wear resistance
salt spray corrosion
