Cast Iron and Types
CAST IRON What is Cast Iron? The iron carbon alloy with more than 2% of carbon and considerable amount of silicon is called Cast Iron. It is produced by melting of pig iron in cupola furnace and its properties are modified by addition of their elements. The resulting product is cast and hence the name Cast Iron. Composition of Cast Iron Carbon 2.5 to 3.7%; Silicon 1.0 to 3.0%; Manganese 0.5 to 1%; Phosphorous 0.1 to 0.9%; Sulphur 0.007 to 0.1%. Carbon is present in iron as free graphite or as cementite. " Graphite in cast iron makes it soft and acts as lubricant, while cementite in cast iron makes it brittle and hard." Silicon has strong graphitising effect; it helps to change cementite to graphite and also it helps from sound castings. Manganese helps to remove sulphur to slag. Phosphorous helps in increasing metal fluidity, but weakens the castings. Sulphur is harmful impurity in cast iron. Sulphur decreases fluidity and increases shrinkage and