SPHERICAL GRAPHITE CAST IRON SEMI-SOLID CASTING METHOD AND SEMI-SOLID CAST PRODUCT

摘要

Provided are a spherical graphite cast iron semi-solid casting method and a semi-solid diecast product with which, in the as-cast state with no heat treatment, even with a small modulus, there is no chilling, spherical graphite in the structure is made even more ultrafine, particle size variability is low, and the number of particles can be made several times greater than in the prior art.This spherical graphite cast iron cast product manufacturing method includes: a melting step; a spheroidizing treatment step; an inoculating step; and a casting step of pouring the molten metal after inoculation to fill a product space through a gate in a die; characterized in that the molten metal prior to filling of the product space is controlled to a semi-solid temperature range. The amount of nitrogen is adjusted such that the amount of nitrogen generated during melting of the cast product is at most equal to 0.9 ppm (by mass). The casting step is performed by controlling the pour temperature and the amount of heat released from the molten metal in such a way that the temperature of a starting material passing through the gate is substantially a fixed temperature between a eutectic temperature and a liquidus temperature.