Study Of Process Characteristics And Nitrided Layer Properties Of Vacuum Nitriding

The present work deals with process characteristics of vacuum nitriding by orthogonal testing design method as well as the mechanical properties and corrosion resistance of the nitrided layer.By altering the process parameters,it is also possible to reduce the porosity and adjust the composition and thickness of the nitrided layer. Emphasis was placed on finding the optimal processing parameters so as to improve the corrosion,wear and fatigue resistance of the nitrided samples.Process parameters such as nitriding pressure,nitriding temperature,nitriding duration and pulse period, were investigated to clear their influence on the microstructure and properties of the nitrided layer.The experimental results obtained have shown that the rate of nitriding can obviously be enhanced by vacuum nitriding.The white layer of the vacuum nitriding is more compact comparing with conventional gas nitriding,and hence the corrosion resistance of the nitrided layer was increased.Comparing data from electrochemistry corrosion experiments showed the effects of vacuum nitriding parameters on the corrosion resistance of the nitrided layers.X-ray diffraction analysis indicated that the compound layer was composted of e andγ′phases which were followed inward byγ′phase andα-Fe.