| 摘要 |
PROBLEM TO BE SOLVED: To provide an inexpensive spheroidal graphite cast iron product which generates no harmful inside shrinkage cavity which causes reduction of strength of structural members, for example underbody components of cars, even when sink head which is sufficient size is not installed or sink head which is the minimum size is installed.SOLUTION: The spheroidal graphite cast iron product is configured by promoting graphite expansion inside so that cancel shrinkage following to solidification for generating no harmful inside shrinkage cavity. With respect to a surface layer part, the number of particles of graphite inside is larger, or the number of particles of graphite inside is larger than that of the surface layer part by 10% or more. |
