Cast Iron

                         Cast Iron The term “Cast iron” identifies a large family of ferrous alloys. These are primarily iron alloys which contain 2% or more carbon and from 1% to 3% silicon. The properties of cast iron can be varied widely by varying the percentages of carbon and silicon, by alloying with various metallic elements, and by varying the practices of melting, casting, and heat treatment. Cast iron in its basic form is a brittle material which has a very little impact strength. It has a little or practically no toughness when compared to low carbon steels.  It has a fraction of the tensile strength of low carbon steels.  When a cast iron piece fails it will not deform in a noticeable way and appears to snap apart or break in a manner consistent with a snap.  There is no early warning of a failure. The graphite phase is pure carbon and acts as a natural defect in the material.  The iron is so saturated with carbon that graphite forms (free carbon) and causes the cast iron to be weaker.  Much smaller amounts of carbon is combined with iron (Fe) in the form of iron carbide (Cementite) which is hard and brittle. Cast irons can be classified as either unalloyed cast irons or alloy cast irons. Unalloyed cast irons are essentially iron-carbon-silicon alloys containing small amounts of manganese, phosphorus, and sulfur. There are other specialty cast irons like austenite gray cast iron and inoculated cast irons.  Cast iron can be alloyed as in carbon steels with elements like Chromium (Cr) and Nickel (Ni) etc. There are basically five types of cast irons. These are gray, ductile, malleable, compacted graphite, and white iron. Except in the case of white cast iron, all other cast irons have...