25CrNiMo钢多元共渗后硬度和耐蚀性分析

Analysis on Hardness and Corrosion Resistance of 25CrNiMo Steel by Multicomponent Infiltration

采用低温气体多元共渗技术对25CrNiMo钢试样进行C、N、O共渗,实现了在材料表面形成均匀的渗层,而且渗层又厚又致密。利用X射线衍射和扫描电子显微技术测定了渗层相的组成及其表面形貌,采用电化学测试技术对渗层在1.0mol/L稀HCl溶液中的耐蚀性与原始材料的耐蚀性进行了对比试验研究,同时对渗层的显微硬度也进行了研究。结果表明,渗层以氧化物、氮化物和碳化物为主,且氮化物居多,渗层约15μm,耐蚀性得到了大大的提高,腐蚀电流密度由原始材料的84.5 mA/cm2降到54.2 mA/cm2,腐蚀速度由0.496 mm/a降到0.318mm/a,其腐蚀速度也低于原始试样的腐蚀速度,其表面硬度最高可达859 HV,是基体显微硬度的3.4倍。

Using low temperature gas multicomponent infiltration technique,carbon,nitrogen and oxygen were infiltrated into the samples of 25CrNiMo steel,the thick,dense and homogeneous infiltration layer was obtained .The phase construction and microstructure of alloying layer were investigated by XRD and SEM. The corrosion resistance of alloying layer and original material was discussed by electrochemical method in 1.0 mol/L HCI solution. And the microhardness was studied by HMV-1T micro-sclerometer. The results show that alloying infiltration layer contains oxide, nitride and carbide,and the nitride is primary. The thickness of alloying infiltration layer is about 15μm. The alloying layer has much better corrosion resistance than original material. The current density reduces from 84.5 mA/cm^2 to 54.2 mA/cm^2 ,and the corrosion rate reduces from 0.496 mm/a to 0.318 mm/a. The maximal surface hardness is 859 HV, 3.4 times that of substrate.