CAST IRON JIGAR RAKHOLIYA PRATIK VALANI SATISH HAPANI NIRAV MULANI

WHAT IS CAST IRON? Cast iron is, as the name implies, "iron" which has been "cast", or melted and poured into a mold. Cast iron is made when pig iron is re-melted in small cupola furnaces and poured into molds to make castings. Cast Iron is generally defined as an alloy of Iron with greater than 2% Carbon, and usually with more than 0.1% Silicon. The cast iron is an eutectic alloy of iron and carbon.

Classifications of Cast Iron Microstructure of White Cast Iron White CI Grey CI CAST IRONS Ductile CI Malleable CI Microstructure of Gray Cast Iron Alloy CI

EFFECT OF IMPURITIES ON CAST IRON Silicon (Si) Sulphur (S) Manganese (Mn) Phosphorus (P)

White Cast Iron Composition of White Cast iron It is a particular variety of cast iron which shows a white fractures. The white colour is due to the fact that the carbon is in the form of carbides known as cementite. It has a high tensile strength and a low compressive strength. Composition of White Cast iron Carbon = 2 to 2.3 % Silicon = 0.85 to 1.2 % Manganese = 0.1 to 0.4 % Phosphorus = 0.05 to 0.2 % Sulphur = 0.12 to 0.35 % .

Gray Cast Iron Composition of gray cast iron It is an ordinary commercial cast iron. The gray colour is due to the fact that the carbon is present in the form of free graphite. It has low tensile strength, high compressive strength and no ductility. Composition of gray cast iron Carbon = 3 to 3.5 % Silicon = 1 to 2.75 % Manganese = 0.4 to 1 % Phosphorus = 0.15 to 1 % Sulphur = 0.02 to 0.15 %

Ductile (Nodular) Iron It is Produced by adding Magnesium to the molten cast iron. It behaves like a steel. Microstructure of Ductile Iron

Malleable cast iron The malleable cast iron is obtained from white cast iron by suitable heat treatment. It is Ductile and may be bent without breaking or fracturing the section. It is used for making machine parts for which the steel forging would be expensive.

Alloy cast iron The alloy cast iron is produced by adding alloying elements like nikel, chromium, molibdenum, copper, silicon and manganese. This alloying elements give more strength and result in improvement of properties. It has increased strength, high wear resistance, corrosion resistance.

Iron-iron Carbide Phase Diagram The iron-iron carbide phase diagram.

Microstructure for Cast Irons Microstructure for cast irons. Magnification: 100x. (a) Ferritic gray iron with graphite flakes. (b) Ferritic ductile iron (nodular iron) with graphite in nodular form. (c) Ferritic malleable iron. This cast iron solidified as white cast iron with the carbon present as cementite and was heat treated to graphitize the carbon.

Applications Essential parts in trains, frames, suspensions, and wheels. differential cases,bearing caps, steering-gear housings, spring hangers, universal-joint yokes, automatic transmission parts, rocker arms, disc brake calipers, wheel hubs, ect... a) Driveline yokes, b) Connecting rods, c) Diesel pumps, d) Steering-gear housing.

Advantages and disadvantages of cast good castability and good fluidility good machinability (graphite cast irons) antivibration properties low stress concentration Sensibility High Compressive Strength

Disadvantages : high brittleness non machinable (white cast iron, chilled cast iron) cold brittleness. Cast iron has good compressive strength but relatively poor tensile strength.