C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
C21D5/00—Heat treatments of cast-iron
C21D5/04—Heat treatments of cast-iron of white cast-iron
C21D5/06—Malleabilising
C21D5/08—Malleabilising with oxidation of carbon
C21D5/10—Malleabilising with oxidation of carbon in gaseous agents