저널

Martensitic stainless steel STS 431 has been nitrided by active screen ion nitriding under the various temperature and time. The thickness of diffusion layer, case depth, hardness and composition phases were investigated using field emission scanning electron microscopy (FE-SEM), micro-Vickers hardness tester, X-ray diffraction (XRD) and glow discharge spectroscopy (GDS). It was observed that the thickness of diffusion layer depends strongly on the treatment temperature and time. A sample, which was nitrided at $450^{circ}C$ for 8hours, was a maximum hardness of Hv0.01 1558 and nitride layer of $70{mu}m$. As shown in XRD patterns, $varepsilon(Fe_{2-3}N)$ and expanded martensite (${alpha}_N$) phases which was saturated with nitrogen solid solution were in the nitrided layer treated at $450^{circ}C$ for 2 hours. Composition phases of $varepsilon$ $(Fe_{2-3}N)$ and ${gamma}`$ ($Fe_4N$) were observed after active screen nitriding at $450^{circ}C$ for 8 hours.

Active screen;Ion nitriding;STS 431;Martensitic stainless steel;Expanded martensite;Wear;