抄録
The eutectic of cast iron forms with a spheroidal crystallization front. The pattern, the number and the size of these eutectic cells vary with the amount of primary austenite and a small amount of so-called third elements, i. e. oxygen, sulphur, manganese and calcium-silicide.
The results obtained are as follows :
i) The number of eutectic cells of pure Fe-C alloy increases with carbon content up to 4.11% C and decreases at higher carbon contents. The former eutectic cells contain flaky graphite and the latter eutctic graphite.
ii) Small amount of oxygen and sulphur decreases the number of eutectic cells of oxygen in cast iron and converts flaky graphite into eutectic.
iii) The inoculation of calcium silicide to the cast iron melts containing oxygen or sulplur increases the number of eutectic cells and converts eutectic graphite into flaky.
iv) The addition of manganese to the cast iron containing sulphur can not completely convert eutectic graphite to flaky.
v) The types of manganese sulphide vary with the ratio Mn/S from massive angular type to elongated anchor type according to the decrease of the ratio.
vi) The inoculation of calcium silicide to the cast iron containing sulphur and manganese produces the small granuler type of manganese sulphide.
