目的 提高Cr18Mn21Mo2.5钢的耐蚀性和耐磨性。方法 使用中频感应炉炼制9种正交设计固溶渗氮用钢，通过正交试验的极差分析得出渗氮效率最高的实验用钢（Cr18Mn21Mo2.5钢），采用高纯氮气在常压下对其进行固溶渗氮处理，同时对渗层的耐蚀性和耐磨性进行测试及机理分析。利用光学显微镜和XRD研究了Cr18Mn21Mo2.5钢及其渗氮层的显微组织及相组成，采用显微硬度测试仪对固溶渗氮后Cr18Mn21Mo2.5钢的硬度分布进行表征，采用电化学工作站及高速载流试验机进行耐蚀性及耐磨性研究。结果 在优化成分后炼制的Cr18Mn21Mo2.5钢具有良好的强度及韧性，对其在1200 ℃下固溶渗氮24 h可以制备出厚度高达1.4 mm的单一奥氏体渗层。渗氮后腐蚀电位提高，腐蚀电流降低。相比于未渗氮试样，渗氮（1200 ℃，24 h）后试样的阻抗弧半径由2500 Ω增大到8000 Ω，摩擦系数由0.33降低到0.28，磨损量从15.5 mg降低到8.7 mg。渗氮后Cr18Mn21Mo2.5钢的耐蚀性及耐磨性明显提高。结论 固溶渗氮后，N固溶到奥氏体晶格间隙中，固溶态的N促进钝化膜再构，同时N的固溶强化使材料表面硬度提高，渗氮层N含量的提高和渗层厚度的增加均有利于提高耐蚀性和耐磨性。

The work aims to improve the corrosion resistance and wear resistance of Cr18Mn21Mo2.5 steel. 9 kinds of orthogonal design solid solution nitriding steel were prepared by medium frequency induction furnace. The test steel with the highest nitriding efficiency (Cr18Mn21Mo2.5 steel) was obtained by the extreme difference analysis of orthogonal test, and the solid solution nitriding treatment was carried out with high purity nitrogen at atmospheric pressure. At the same time, the corrosion resistance and wear resistance of the nitriding layer were tested and analyzed. The microstructure and phase composition of Cr18Mn21Mo2.5 steel and its nitriding layer were studied by optical microscope and XRD. The hardness distribution of Cr18Mn21Mo2.5 steel after solid solution nitriding was characterized by microhardness tester. The corrosion resistance and wear resistance of Cr18Mn21Mo2.5 steel after solid solution nitriding were studied by electrochemical workstation and high speed current carrying tester. Single austenite layer with thickness as high as 1.4 mm (1200 ℃, 24 h) could be prepared under the optimized preparation process because the prepared Cr18Mn21Mo2.5 had excellent strength and flexibility. After the nitriding, the corrosion potential was improved and the corrosion current was reduced. Compared with the unnitriding sample, the impedance arc radius of the nitrided (1200 ℃, 24 h) sample increased from 2500 Ω to 8000 Ω, the friction coefficient decreased from 0.33 to 0.28, and the wear weight loss decreased from 15.5 mg to 8.7 mg. After nitriding, the corrosion resistance and wear resistance of ACr18Mn21Mo2.5 steel were improved obviously. After solid solution nitriding, N enters into Austenite lattice gap and solid solution N promotes the reconstruction of passivation film. At the same time, the solid solution strengthening of N improves the surface hardness of material. The increase of N content and the thickness of nitriding layer are beneficial to improving the corrosion resistance and wear resistance.