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Spheroidal graphite cast iron is a material with a wide range of uses such as in automobile parts. By applying active screen plasma nitriding (ASPN) treatment, the use of spheroidal graphite cast iron is expanded, and it can be expected to be used under special load conditions. In this study, we evaluated the effect of ASPN treatment on the mechanical properties of spheroidal graphite cast iron. With ASPN treatment, a nitride layer was formed on the sample surface and a diffusion layer was formed further inside the nitride layer. The thickness of nitride layer increased as the treatment temperature increased. The hardness was improved by ASPN treatment. The abrasion resistance was improved by ASPN treatment, and longer treatment time resulted in higher abrasion resistance. The fatigue strength was improved by ASPN treatment, and longer treatment time resulted in higher fatigue strength. ASPN treatment also improved the corrosion resistance.

In the active screen plasma nitriding (ASPN) method, the material to be processed is insulated. A mesh-like metal screen is placed around the material to be used as the cathode and a furnace wall is used as the anode. In this study, the effect of ASPN treatment on the fatigue characteristics of austenitic stainless steel was investigated. Nitride layers of varying thicknesses were formed by varying the treatment time to energize the treated material without insulation. A direct-current plasma nitriding apparatus was used for active screen plasma nitriding treatment. The nitriding treatment was performed at an N 2 :H 2 concentration ratio of 1:1 for 28.8172.8 ks at 673 K and 100 Pa. The thickness of the nitride layer increased as the treatment time increased. The fatigue strength increased as a result of the ASPN treatment. Furthermore, the fatigue strength increased as the thickness of the nitride layer increased.