Effect of Melting Conditions on Chill Formation of Spheroidal Graphite Cast Iron by Metallic Mold Casting

Abstract

  The effects of melting conditions on the chill formation of spheroidal graphite iron cast into metal mold were investigated. The influence of melting conditions on chill formation became apparent at 1400 ℃ or lower at which the reaction of magnesium contained in the spheroidizing additives during the spheroidizing treatment became mild. Chill formation tendency was changed by the melting conditions of the parent iron alloy used for sample melting, melting temperature and atmosphere and addition of iron oxide at the time of sample preparation. All chills in this experiment were reverse chill. Chill formation was suppressed by setting the amount of oxygen of the base molton iron before the spheroidizing treatment to 20 to 30 ppm, and even when the amount of oxygen of the base molten iron was too high or too low, chill was generated.