Ductile cast iron (spheroidal graphite cast iron) is a material that, by adding magnesium and other elements to molten metal and causing graphite to crystallize into a spherical shape, maintains the excellent castability of gray cast iron while imparting high tensile strength, excellent ductility, toughness, and impact resistance. By adjusting the matrix structure to ferrite, pearlite, or a mixed structure thereof, it is possible to develop various properties such as wear resistance and machinability. The main manufacturing process is casting, after which it is finished into its final shape through machining processes such as cutting and grinding. It is widely used in a wide range of industrial fields where high reliability and strength are required, such as automotive parts (crankshafts, hubs), construction machinery parts, water pipes, and manhole covers.