| 摘要 |
PURPOSE:To obtain spheroidal graphite cast iron having superior mechanical characteristics and a fine appearance after working by providing a specified composition, forming a bainite structure by slow cooling, and regulating the grain size to a specified value or below. CONSTITUTION:Spheroidal graphite cast iron consisting of, by weight, 2-4% C, 1.5-3% Si, <0.5% Mn, 4-6% Ni, 0.3-2.5% Cu, 0.2-1% Mo, 0.02-0.07% Mg and the balance Fe with inevitable impurities is cast and cooled. In the cooling stage, slow cooling is carried out at 0.1-10 deg.C/min average cooling rate in the temp. range of 700-200 deg.C to regulate the grain size to <=100mum as well as to form a bainite structure as the matrix structure.
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