鋳鉄のチル組織と共晶度および接種の関係

Abstract

In our preceding investigation(1)(4) on the solidification process of cast iron, it was found that the eutectic solidification of flake graphite is neucleated by primary austenite in hypo-eutectic composition or by primary graphite in hyper-eutectic alloys. Then, the solidification process would be abnormal in iron of eutectic composition. The process might be influenced by the inoculation such as with calcium-silicide or ferrosilicon and also be correlated in some manner with the structure of undercooled graphite containing titanium. In this report the effects of saturation degree and inoculation on the chill structure of flake graphite or undercooled graphite cast iron are studied. The depth of chill decreases as the saturation degree increases, but there appears an abnormal chill in low silicon alloy and undercooled graphite in high silicon alloy when the compositions of the alloys are approximately that of the eutectic. The inoculating effect of calciumsilicide is stronger than that of ferrosilicon in hypo-eutectic flake graphite iron, but the former is less effective than the latter in hyper-eutectic iron, and in the alloy with the structure of undercooled graphite containing titanium, inoculation of ferrosilicon is always more effective than that of calcium-silicide.