Cast iron billet excelling in workability and process for producing the same

摘要

The present invention provides tough cast iron and cast iron semi-finished products excellent in workability without heat treatment requiring massive heat energy and long time and a method of production enabling these to be efficiently produced, that is, cast iron of ingredients of white cast iron where particles of spheroidal graphite or flattened graphite are dispersed, cast iron where the ingredients of the white cast iron satisfy, by wt %, (% C)<=4.3-(% Si)/3 and C>=1.7% and where the particles of spheroidal graphite are dispersed at a density of 50 particles/mm² or more, or cast iron where the particles of flattened graphite have a width of 0.4 mm or less and a length of 50 mm or less.