F51双相不锈钢离子渗氮层的组织与性能

目的提高F51双相不锈钢的硬度以及耐磨性能。方法将F51双相不锈钢进行低温(450℃)和高温(550℃)离子渗氮处理,利用光学显微镜(OM)、扫描电子显微镜(SEM)观察F51双相不锈钢渗氮层的微观组织,利用X射线衍射(XRD)方法对渗氮层沿深度方向相组成的变化进行分析,采用显微硬度计、摩擦磨损实验机分别对渗氮层的显微硬度及耐磨性能进行测试,采用激光扫描共聚焦显微镜(LSCM)对磨痕形貌进行观察。结果F51双相不锈钢低温渗氮层主要由N相组成,由表及里为N N+N(少量);高温渗氮层主要由CrN+N相组成,由表及里为CrN+N N+N。高温渗氮层厚度约为低温渗氮层厚度的3倍。低温渗氮样品的平均表面硬度约为基体表面硬度的3.5倍;高温渗氮样品的平均表面硬度约为基体硬度的4倍。基体的摩擦系数约为0.71,低温和高温渗氮处理后样品的摩擦系数大大降低,分别为0.24和0.17。渗氮样品磨痕的宽度和深度较基体显著降低。结论F51双相不锈钢低温渗氮层主要由N相组成,高温渗氮层主要由CrN+N相组成,两种温度渗氮后的样品硬度和耐磨性均得到显著提高。

Microstructure and Properties of Plasma Nitrided F51 Duplex Stainless Steel

The paper aims to improve the hardness and wear resistance of F51 duplex stainless steel.The F51 duplex stainless steel was nitrided at 450℃and 550℃.The microstructure of the nitrided layer of F51 duplex stainless steel was observed by optical microscopy(OM)and scanning electron microscopy(SEM).The phase composition change of the nitrided layer in different depth was measured by X-ray diffraction(XRD).The microhardness and the wear resistance were evaluated by microhardness tester and friction wear tester respectively.The surface wear tracks were observed by laser scanning confocal microscope(LSCM).The low-temperature nitrided layer of F51 duplex stainless steel was mainly composed of phasegN and the phase distribution from the surface to the inner wasgN®gN+aN(little).The high-temperature nitrided layer was mainly composed of phases CrN+aN,the phase distribution from surface to the inner was CrN+aN®aN+gN.The high-temperature nitrided layer was 3 times thicker than the low-temperature nitrided layer.The average surface hardness of the low-temperature nitrided sample was 3.5 times as high as the untreated sample;while the average surface hardness of the high-temperature nitrided sample was 4 times as high as the untreated sample.The friction coefficient of untreated sample was 0.71.While the friction coefficients of low-temperature and high-temperature nitrided layers were greatly reduced,which were 0.24 and 0.17,respectively.The width and the depth of surface wear tracks of the nitrided samples were reduced obviously compared with the untreated sample.The low-temperature nitrided layer of F51 duplex stainless steel mainly consists of phasegN,and the high-temperature nitrided layer mainly consists of phases CrN+aN.Both hardness and wear resistance of nitrided samples are effectively improved.