| 摘要 |
PURPOSE:To produce a thick-walled ductile cast iron having excellent ductility and toughness by subjecting a spheroidal graphite cast iron contg. specific compsn. ratios of C, Si, Mn, P, S, Ni, and Mg to specific hot working and holding the cast iron at a specific temp., then cooling the same. CONSTITUTION:The spheroidal graphite cast iron contg. 3.0-4.0wt.% C, 1.5-25.% Si, <=0.50% Mn, <=0.030% P, <=0.010% S, <=1.0% Ni, and 0.020%n0.100% Mg is subjected to 5-50% hot rolling in a 110-700 deg.C range by rolling down, hot forging, etc. The graphite is thereby extended and the casting defects such as porous shrinkage cavities are compressed. The cast iron after the hot working is held for 4-40hr in a 700-600 deg.C range to convert austenite to ferrite. This cast iron is cooled down to room temp. by air cooling, etc. The thick-walled ductile cast iron having the excellent mechanical properties to the center of the thickness and the excellent ductility and toughness is thereby easily obtd. |
