Method for producing die-cast product of spherical graphitic cast iron including ultrafine spherical graphite, and spheroidizing treatment agent

A producing method of a die-cast product of a spherical graphite cast iron comprising following processes sequentially;

• a melting process, in which raw material comprising cast iron is melted by heating and
• an original molten metal is obtained;
• a spheroidizing process, in which a spheroidizing is carried out;
• an inoculation process, in which an inoculation is carried out;
• and
• a casting process, in which a casting in a metal mold is carried out;
• wherein the spheroidizing is carried out by using a spheroidizing agent, in which a C amount is 0.5 mass % or more, a total nitrogen amount N is 150 ppm (by mass) or less, and a nitrogen amount generated during melting is 15 ppm (by mass) or less;
• wherein the obtained
• original molten metal is heated to a predetermined temperature of 1,500° C. or higher, heating is then
• stopped and the original molten metal is hold at the predetermined temperature to remove oxygen from the original molten metal, the
• original molten metal is cooled to reduce nitrogen in the original molten metal;
• and then the spheroidizing, the inoculation and the casting are carried out.