| 摘要 |
PURPOSE:To obtain a cast iron having additionally high strength and toughness in a method for casting a molten cast iron which is decreased in carbon equiv. and subjected to a spheroidization treatment to a white cast iron casting and holding the same at a high temp. under prescribed conditions by cooling quickly the casting at the bainite precipitation temp. after the holding at the high temp. CONSTITUTION:The molten cast iron of 2.0-4.3% carbon equiv. is subjected to the graphite spheroidization treatment and is then die-cast and is quickly cooled to solidify. The white cast iron casting obtd. in such a manner is subjected to the high-temp. holding to precipitate finely and spheroidally graphite and to convert the base to austenite at the same instant. The casting is then quickly cooled to and held at the bainite precipitation temp. to convert the base to bainite. The fine spheroidal graphite is thus dispersed and precipitated in the casting and the base structure is made to the bainite, by which the spheroidal graphite iron having the excellent toughness and strength not possible heretofore is obtd. |
