PRODUCTION OF SPHEROIDAL GRAPHITE CAST IRON CONTAINING AS-CAST FERRITE AS BASE STRUCTURE IN DIE CASTING

摘要

PURPOSE:To obtain a titled cast iron contg. as-cast ferriete as a base structure by pouring a molten cast iron consisting of prescribed chemical components contg. an element for accelerating graphite spheroidization into a die formed of a copper alloy having high heat conductivity then passing water through the die to cool forcibly the die. CONSTITUTION:A molten metal contg. the chemical components consisting of 3.4-4.0% C, =2.7% Si, =0.3% Mn, =0.1% P, =0.02% S and =0.03% Mg and the balance Fe is cast into a die formed of a copper alloy having 0.2-0.8 cal/cm2.sec. deg.C heat conductivity and cooling water is passed through the die to cool forcibly the die upon completion of the pouring. Super cooling arises in the molten metal as the molten metal is cooled in this stage. As a result, the distance among the graphite particles is decreased, by which the deposition of the carbon atom to the gaphite particles is made easy in the stage of the A'r1 transformation and the formation of ferrite is accelerated. The spheroidal graphite cast iron which contains the as-cast ferrite as the base structure, has high elongation and yield strength and is provided with the mechanical properties strong to impact force is thus obtd. without subjecting the molten metal to an annealing stage.