目的 在AISI 300系列奥氏体不锈钢表面制备单一S相渗氮层，提高该系列不锈钢渗氮层的硬度、抗磨损性能，对比揭示渗氮前后不锈钢的磨损机制。方法 采用低温辉光等离子渗氮技术(LTPNT)在AISI 300系列奥氏体不锈钢表面制备渗氮层。利用光学显微镜(OM)、扫描电子显微镜(SEM)、电子探针(EPMA)、X射线衍射仪(XRD)分析渗氮层的截面形貌、元素分布和物相组成;通过比磨损率和磨痕形貌分析渗氮层的摩擦学性能;利用电化学实验考察渗氮前后3种不锈钢的耐蚀性。结果 AISI 300系列奥氏体不锈钢经380 ℃、12 h处理后，其表面获得了厚度为15 μm左右、与基体致密结合、组织成分均匀的渗氮层;渗氮层的相结构主要为S相，无CrN相析出;经渗氮后，该系列不锈钢表面硬度均为1 100HV左右，较基体硬度提高了5倍左右;不锈钢基体的磨损机理为黏着和磨粒磨损，经渗氮后转变为氧化磨损和微切削;渗氮层的比磨损率约为不锈钢基体的1/20，抗磨损的能力得到显著提升;在25 ℃环境温度下渗氮后，304L、316L和321的自腐蚀电位下降，腐蚀电流密度增加，腐蚀速率加快，耐腐蚀性能稍有降低。通过对比腐蚀形貌发现，渗氮层仍具有一定的耐蚀性能。结论 通过LTPNT可以获得高硬度、组织均匀致密、结合强度高的渗氮层，渗氮层中S相的存在可以显著提高AISI 300系列奥氏体不锈钢的表面硬度、抗磨损能力，降低其摩擦因数和比磨损率，对延长不锈钢的服役寿命有着积极的作用。

This advanced surface strengthening technology can improve the anti-wearing properties of stainless steel without altering the original material properties of the matrix. The work aims to prepare a single S-phase nitriding layer on the surface of AISI 300 series austenitic stainless steel by low-temperature plasma nitriding technology (LTPNT) to improve the hardness and anti-wearing properties of stainless steel and compare the wear mechanisms of stainless steel before and after nitriding. The effect of the nitriding layer on the hardness, anti-wearing properties, and wear mechanism of stainless steel was investigated. Three widely used Cr-Ni commercial steels (AISI 304L, AISI 316L, and AISI 321) were sliced into 15 mm ′ 15 mm ′ 5 mm rectangular cubes, which were mechanically ground and polished. Nitrided samples at 380 ℃ for 12 hours were the major process parameters for LTPNT. The nitrided samples were mechanically polished and etched with marble mordents (Cu2SO4+HCl+distilled water). A metallographic microscope (AxioCam MRc5 ZEISS) was used to observe the cross-sectional morphology of the nitrided samples. The elemental distribution and phase composition of the nitriding layer were analyzed by EPMA and XRD (D/max-2400). The tribological properties of nitriding layer were characterized by specific wear rate and corrosion morphology. The wear microstructures of the samples were observed by a scanning electron microscope (QUATA FEG450). The corrosion resistance of samples was evaluated by an electrochemical experiment (CHI600E electrochemical workstation). In addition, wear tests were performed on material surface with performance comprehensive tester (CFT-I), and the surface and cross-sectional hardness were measured with a vicker microhardness meter (MVC-1000JMT1). The nitriding layer was uniform and dense, with a thickness of 15 μm approximately. The primary phase of the nitriding layer was the S-phase, but the Cr-N phase was not precipitated in the layer, indicating that nitriding did not deteriorate the corrosion resistance of the steel matrix. 304L nitriding layer consisted of supersaturated austenite (S-phase), a small amount of hard phase (γ′-Fe4N), whereas the nitriding layers of 316L and 321 consisted of S-phase. The surface hardness of the nitrided samples was about 1 100HV, which was about 5 times higher than that of untreated samples. The wear mechanism of three stainless steels changed from abrasive and adhesive wear to oxidation wear and micro-grooves. The specific wear rate of the steel matrix was about 20 times higher than that of nitrided samples, indicating that LTPNT could significantly improve the wear resistance. The corrosion current density of the three steels after nitriding was higher than that of the matrix slightly, which indicated a decrease in free corrosion potential after nitriding. The corrosion resistance of steels decreased to varying degree. Nitriding changed the corrosion mechanism of steels from uniform corrosion to local corrosion. Therefore, the enhancement of surface strengthening techniques for different materials was different, so a suitable surface strengthening process and parameters were required. The nitriding layer with high surface hardness and binding strength can be formed on the steel matrix with LTPNT. The metallograph of the nitriding layer is stable and dense. S-phase in the nitriding layer can significantly improve the surface hardness and anti-wearing properties of the steel and meanwhile it decreases the friction coefficient and specific wear rate. In summary, LTPNT can positively extend the service life of stainless steel.