Correct Answer - Option 2 : Ductile cast iron
Explanation:
Cast Iron:
The term cast iron, like the term steel, identifies a large family of ferrous alloys. Cast irons are multicomponent ferrous alloys. They contain major (iron, carbon, silicon), minor (<0.01%), and often alloying (>0.01%) elements.
Cast iron has higher carbon and silicon contents than steel.
In general, the types of cast iron are
- Grey cast iron
- White cast iron
- Malleable cast iron
- Spheroidal or nodular cast iron
- Austenitic cast iron
Spheroidal or nodular cast iron:
Spheroidal graphite cast iron also referred to as ductile iron or nodular cast iron, is essentially a variety of cast iron in which the graphite is present in the form of spheroids, rather than flakes as in normal gray iron, or compacted aggregates (nodules) as in malleable iron.
- The presence of cerium and magnesium causes the graphite to precipitate during the solidification of molten alloy in the form of small spheroids. These spheroids result in less concentration effect as compared to the flakes in the grey iron resulting in high ductility, strength, toughness, and stiffness of a material.
- Ductile cast iron is used for making machine parts like axles, brackets, levers, crankshaft housing, die pads and die shoes.
White Cast iron:
It is white because carbon is in the form of carbide known as cementite which is the hardest constituent of Iron
- n content in White Cast Iron is 1.75 to 2.3%.
- It has high tensile strength, low compressive strength, and high brittleness.
- It is used in abrasion-resistant parts where it's brittleness is of minimum concern such as shell liners, slurry pumps, ball mills, lifter bars, extrusion nozzles, cement mixers, pipe fittings, flanges, etc.
Grey Cast iron:
- The carbon content in Grey Cast Iron is 2.5 to 3.5%.
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It is grey because carbon is present in the form of free Graphite.
- High compressive strength, low tensile strength, and easily machinable
Malleable cast iron: It is a heat-treated iron-carbon alloy
- The graphite structure is formed into irregularly shaped spheroidal particles
- Malleable cast iron is produced from white cast iron by annealing.
- During annealing treatment graphite nucleates and grows from the Fe3C to form nodules.
