| 摘要 |
PURPOSE:To obtain high strength cast iron parts whose fatigue strength has been elevated, by heating a ductile cast iron material, hot-forging it, forming a ferrite layer on the surface, and after that, performing a soft nitrising treatment. CONSTITUTION:A cast iron material is obtained by casting a ductile cast iron material, hot forging is performed by heating to 800-950 deg.C, and a ferrite layer is formed on the surface. Subsequently, a soft nitrising treatment is performed by a gas soft nitrising method, etc. According to this method, a uniform nitrising layer and a diffusion layer can be obtained, and the inside of the cast iron material is maintained as it is, therefore, its mechanical strength is not obstructed, and it is possible to obtain high strength ductile cast iron parts having a nitriding layer on the surface. |
