| 摘要 |
PROBLEM TO BE SOLVED: To provide spheroidal graphite cast iron having excellent low temperature toughness in which sufficient toughness can be provided even in an environment of≤-60°C, and to provide a production method therefor. SOLUTION: The absorbed energy value in a Charpy impact test at -60°C or -80°C of the spheroidal graphite cast iron is controlled to≥14 J/cm<SP>2</SP>by preparing a composition comprising, by mass, 2.0 to 4.0% carbon, 0.01 to 0.1% of one or more spheroidizing acceleration elements selected from magnesium, calcium and rare earth elements, 1.0 to 3.0% silicon, and≤0.02% sulfur, and the balance iron with inevitable impurities, and controlling the contents of elements other than cobalt, copper and nickel in the inevitable impurities to trace amounts as possible. In the production method therefor, an alloy having a composition comprising carbon, silicon and sulfur in the above componential amounts, and the balance iron with trace amounts of inevitable impurities is melted in a cold crucible melting furnace 10, thereafter, a spheroidizing treatment agent comprising the above spheroidizing acceleration elements is added thereto, and the alloy is cooled without performing inoculation treatment. COPYRIGHT: (C)2004,JPO
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