目的 研究不同放电电流密度下，渗氮层组织及摩擦学性能随时间的演变规律，以及氮在不锈钢中的扩散与析出机制。方法 采用热丝增强等离子体辅助渗氮方法，对奥氏体不锈钢表面进行改性。采用XRD及XPS研究渗氮层相组成及结构；采用SEM观察渗氮层的横截面形貌，并利用能谱分析氮含量及其随深度的分布情况；分别使用纳米压痕仪、磨损仪及台阶仪研究渗氮层的摩擦学性能。结果 当电流密度为0.81 mA/cm2时，短时间（1~2 h）渗氮后，不锈钢表面形成单一过饱和固溶体相；渗氮时间增加到4 h后，转变为更稳定的Fe4N相，渗氮层厚度达14.2 μm，表面硬度达17.81 GPa。当电流密度增加到1.25 mA/cm2时，N与金属原子间结合能增加，渗氮1 h开始析出CrN和Fe4N相，4 h后表面硬度和模量分别达22.88 GPa和314.2 GPa，磨损量仅为基体的0.53%。结论 氮原子在奥氏体中的扩散系数随电流密度成正比增加。当渗氮时间（或热丝电流）增加，渗氮层厚度与维氏硬度明显增加，其增加趋势正比于时间的1/2次幂，结构由单一固溶体相γN转变为固溶体与少量氮化物析出相CrN和Fe4N，渗氮层的摩擦学性能明显提高。

The work aims to study the evolution of nitriding layer structures and tribological properties with time under different discharge current densities and the diffusion and precipitation mechanism of nitrogen in stainless steel. The surface of austenitic stainless steel was modified by hot wire enhanced plasma assisted nitriding. The phase composition and structure of nitriding layer were studied by XRD and XPS, the cross-section morphology of nitriding layer was observed by SEM, and the nitrogen content and distribution with depth were analyzed by energy spectrum. The tribological properties of nitriding layer were studied by nano-indentation, wear tester and step tester, respectively. When the current density was 0.81 mA/cm2, a single supersaturated solid solution phase was formed on the surface of stainless steel after nitriding for a short time (1~2 h). As nitriding time increased to 4 h, the phase was converted to more stable Fe4N phases, the thickness of nitriding layer reached 14.2 μm, and the surface hardness reached 17.81 GPa. When the current density increased to 1.25 mA/cm2, the binding energy between N and metal atoms increased, and the CrN and Fe4N phases began to precipitate after nitriding for 1 h. After 4 h, the surface hardness and modulus increased to 22.88 GPa and 314.2 GPa, respectively, and the wear rate was only 0.6% of that of the substrate. The diffusion coefficient of N atom in austenite increases in direct proportion to current density. With the increase of nitriding time (or hot-wire current), the thickness of nitriding layer and Vickers hardness increase obviously. The increasing trend is proportional to one-half power of time. The single solid solution phase γN of nitriding layer is transformed into solid solution phase CrN and Fe4N with a small amount of nitride precipitates. The tribological properties of nitriding layer are improved obviously.