| 摘要 |
PROBLEM TO BE SOLVED: To provide a method for producing high strength spherical graphite cast iron which has no casting defects, has good dimensional precision, contains fine crystal grains to the inside, and has high hardness even when its thickness is increased. SOLUTION: The molten metal of spherical graphite cast iron having a composition containing, by weight, 3.0 to 4.0% C, 1.5 to 3.0% Si, 0.1 to 1.0% Mn and 0.03 to 0.1% Mg, and the balance iron, and further having components containing 0.1 to 1.0% Cr, 0.5 to 2.5% Ni, 0.1 to 1.0% Cu and 0.001 to 0.01% Bi or 0.001 to 0.01% Sb or 0.001 to 0.01% Te is cast into a mold obtained by filling heat resistant zircon or chromite sand into the surface of a cavity in the mold to a thickness of 20 to 50 mm, and hardening the same into a facing sand layer, and filling facing sand whose outside has been strengthened by an iron rod or the like therein, and hardening the same into a back sand layer, so that a sound casting stock can be obtained.
|
