| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide spheroidal graphite cast iron which can control chilling in a thin-walled part and is provided with high characteristics as a vehicle component even when a spheroidizing agent not containing a rare earth element is used. <P>SOLUTION: In a ladle, a spheroidizing process using a spheroidizing agent of an Fe-Si-Mg-based alloy not containing a rare earth element and an inoculation process using an Fe-Si-based inoculation agent are performed on molten metal, and then a molten steel pouring flow inoculation process using an Fe-Si-based inoculation agent containing, in mass ratio, 45-75% of Si, 1-3% of Ca, and 15 ppm or less of Ba, with the input of 0.20-0.40% in mass ratio relative to the molten metal, is performed before the molten metal is cast in a mold. Thus, the spheroidal graphite cast iron having the final composition, which includes, in mass ratio, 3.0-4.5% of C, 3.0-4.5% of Si, 0.2-0.4% of Mn, 0.006-0.020% of S, 0.08-0.30% of Cu, 0.020-0.040% of Sn, and 0.015-0.050% of Mg, with the balance of Fe and unavoidable impurities, is obtained. <P>COPYRIGHT: (C)2013,JPO&INPIT |
