Spheroidal graphite cast iron for crank shafts and a crank shaft manufactured from such cast iron

摘要

Spheroidal graphite cast iron for crank shafts having a tensile strength of 75 kgf/mm.sup.2 or more, and having excellent conformability and machinability, which cast iron consisting, by area ratio, of graphite of 5 to 15%, ferrite of not more than 10%, and the balance pearlite matrix, said cast iron having a Brinell hardness (HB) of 241 to 277.