Study On Microstructure And Property Of Plasma Nitrided 3Cr13 Martensitic Stainlesssteel

In this paper,3Cr13 martensitic stainless steel was nitrided at different temperature.The microstructure characteristics,layer phase composition distribution and composition distribution of the nitrided layer were investigated by optical microscopy(OPM),scanning electron microscopy(SEM),X-ray spectrometer and delamination(EDS),X-ray diffraction(XRD).The top surface hardness and the hardness distribution of the nitrided layer were evaluated by micro hardness tester.The surface friction and wear properties and corrosion resistance before and after nitriding were also tested.Thesis results are as follows:450? nitrided:(1)Nitriding layer is mainly composed of compound layer(about 45?m)and diffusion layer(about 15?m).Nitrided layer is mainly composed of nitrogen-martensite(?'N),?-Fe2-3N phase and a small amount of CrN nitride.(2)The phase distribution along direction that nitrided layer to substrate is:CrN+?-Fe2-3N?Fe3N??'N??N.The average surface hardness of nitrided layer is 700HV,which is 2.5 times than the substrate.(3)The result of the XRD peeling layer shows that the expansion of the lattice is decreasing as the layer of the layer of the skin deep,?'N and the(110)and the(200)crytal surface diffraction peaks move towards the the high angle.Secondly,the kurtoid is gradually decreasing.(4)The corrosion resistance of nitrided sample improves significantly.Apparent passive region appears.500? nitrided:(1)Nitriding layer is mainly composed of compound layer(about 60?m)and diffusion layer(about 40?m).The compound layer is mainly composed of nitride phase CrN?Fe4N??-Fe2-3N and a small amount of nitrogen-martensite(a'N).Diffusion layer is single nitrogen-martensite(?'N)phase.(2)The phase distribution along direction that nitrided layer to substrate is:CrN+?-Fe2-3N+ Fe4N+?'N??-Fe3N+?'N??'N??N.The average surface hardness of nitrided layer is 1100HV,which is 4 times than the substrate.(3)Compound layer containing nitrogen-martensite ?'N did not show the observable lattice expansion,but in the diffusion layer of nitrogen martensite ?'N observable lattice expansion,and(110),(211),(220)crystal plane expansion is different.(4)The coefficient of friction of nitrided sample is reduced.