MOLDING METHOD FOR MELTING MAGNESIUM ALLOY SOLID CRYSTALLIZED IN GRANULE SHAPE INTO METAL PRODUCTS IN SOLID-LIQUID COEXISTING STATE BY PRESSURE CASTING MEANS AND METAL PRODUCTS MOLDED THEREBY

摘要

PURPOSE: To provide a new pressure casting method capable of stably molding metal products with good metal structure by setting solid grain diameter and solid phase ratio of the semi-solid into a desired state for molding in a magnesium alloy molding method for melting a solid material crystallized in a granule shape into a semi-solid with thixotropy in the semi-solid coexisting state and molding thixotropy into a mold. CONSTITUTION: In a molding method for cooling molten magnesium alloy in a semi-liquid state including a solid phase, cooling the semi-liquid state into a solid material in which solid phase is crystallized into a granule shape, and molding the solid material into semi-liquid magnesium alloy so that the semi-liquid magnesium alloy is pressure cast in a mold, the pressure casting method of magnesium alloy comprises the steps of setting a ratio of primary crystal of the solid material to 55 to 65%; melting the solid material into a semi-liquid in the solid-liquid coexisting state by a selected heating temperature such that the semi-liquid has a primary solid phase size of 50 to 250 μm and a solid phase ratio of 30 to 70% in a semi-solid state; and pressure casting the semi-liquid into a mold through a nozzle while maintaining the semi-solid state so that the semi-liquid is molded into metal products having a primary crystal ratio of 20 to 50% in the mold.