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

Abstract

The present invention provides a producing method of a die-cast product of a spherical graphite cast iron 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, in a producing method of a sand mold cast product of a thin walled spherical graphite cast iron having a melting process, a spheroidizing process, an inoculation process, and a casting process.

1 . A producing method of a die-cast product of a spherical graphite cast iron comprised from;
 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.   
     
     
         2 . The producing method of the die-cast product of the spherical graphite cast iron according to  claim 1 , wherein the spheroidizing agent is a Fe—Si—Mg-based spheroidizing agent. 
     
     
         3 . The producing method of the die-cast product of the spherical graphite cast iron according to  claim 1 , wherein the nitrogen amount generated during melting of the die-cast product is controlled to 5 ppm (by mass) or less. 
     
     
         4 . The producing method of the die-cast product of the spherical graphite cast iron according to  claim 1 , wherein raw material comprising cast iron is melted by heating and an original molten metal is obtained; the original molten metal is heated to a predetermined temperature of 1,500° C. or higher, heating is stopped and the original molten metal is hold at the predetermined temperature for a certain time to remove oxygen from the original molten metal, the original molten metal is gradually cooled to reduce nitrogen in the original molten metal; and the spheroidizing, the inoculation and the casting are carried out. 
     
     
         5 . 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. 
     
     
         6 . The spheroidizing agent according to  claim 5 , wherein the spheroidizing agent is a Fe—Si—Mg-based spheroidizing agent. 
     
     
         7 . The spheroidizing agent according to  claim 5 , wherein the spheroidizing agent is a Fe—Si—Mg-based spheroidizing agent applicable to sand mold thin walled spherical graphite cast iron that has the same solidification cooling conditions as the metal mold.