SPHEROIDAL GRAPHITE CAST IRON WITH SUPERIOR OXIDATION RESISTANCE AT HIGH TEMPERATURE AND SUPERIOR THERMAL FATIGUE RESISTANCE

摘要

PURPOSE:To obtain spheroidal graphite cast iron having a ferrite matrix as cast and showing enhanced oxidation resistance at high temp. and enhanced thermal fatigue resistance, by adding very small amounts of Mg, Ce and Le to a steel contg. specified amounts of C, Si, Mn, P, S and Mo. CONSTITUTION:This spheroidal graphite cast iron consists of, by weight, 2.5- 3.8% C, 3.5-4.8% Si, =1.0% Mn, =0.1% P, =0.1% S, 0.5-2.0% Mo, 0.03-0.1% Mg, 0.02-0.5% of at least one of Ce and La, and the balance Fe. By the composition a matrix contg. =90% ferrite is obtd. as cast, and the added Ce and La improve the oxidation resistance at high temp. and maintain the high thermal fatigue resistance. Accordingly, the spheroidal graphite cast iron can be suitably used as the material of an exhaust manifold for a car, etc.