This study aims to draw an exact boundary for microstructural and mechanical behaviors in terms of pulsed plasma nitriding conditions. The pulsed plasma nitriding treatment was applied to AISI 304 austenitic stainless steel at different temperatures and durations. Results reveal that nitriding depth increased as process temperature and duration increase. The nitriding depth remarkably increased at 475°C for 8 h and at 550°C for 4 h. An austenite structure was transformed into a metastable nitrogen-oversaturated body-centered tetragonal expanded austenite (S-phase) during low-temperature plasma nitriding. The S-phase was converted to CrN precipitation at 475°C for 8 h and at 550°C for 4 h. Surface hardness and fatigue limit increased through plasma nitriding regardless of process conditions. The best surface hardness and fatigue limit were obtained at 550°C for 4 h because of the occurrence of CrN precipitation.

这项研究的目的是根据脉冲等离子体渗氮条件为微观结构和力学行为绘制一个精确的边界。在不同的温度和持续时间下，将脉冲等离子体氮化处理应用于AISI 304奥氏体不锈钢。结果表明，渗氮深度随过程温度和持续时间的增加而增加。氮化深度在475°C下持续8 h和在550°C下持续4 h显着增加。在低温等离子体渗氮过程中，奥氏体结构转变为亚稳态的以氮为中心的过饱和体心四方膨胀奥氏体（S相）。S相在475°C下8 h和550°C下4 h转化为CrN沉淀。不论工艺条件如何，通过等离子渗氮均可提高表面硬度和疲劳极限。