Question

The percentage of carbon in cast iron varies from:
1. 0.1 to 0.5
2. 0.5 to 1
3. 1 to 1.7
4. 1.7 to 4.5

Answer 1

Correct Answer - Option 4 : 1.7 to 4.5

Explanation:

Cast iron 

• It is an alloy of iron, carbon, and silicon and it is hard and brittle.
• Carbon content in CI may be within 1.7% to 3% and carbon may be present as free carbon or iron carbide Fe3C.
• In general, the types of cast iron are

1. Grey cast iron and
2. White cast iron
3. Malleable cast iron etc.

Wrought iron

• Wrought iron is a very pure iron where the iron content is of the order of 99.5%. 
• It is produced by re-melting pig iron and some small amount of silicon, sulfur, or phosphorus may be present. It is tough, malleable, and ductile and can easily be forged or welded.
• It cannot however take the sudden shock. Chains, crane hooks, railway couplings, and such other components may be made of this iron.

Pig iron

• Pig iron is an intermediate product of the iron industry. 
• Pig iron has a very high carbon content, typically 3.8–4.7%, along with silica and other constituents of dross, which makes it very brittle, and not useful directly as a material except for limited applications.

Steel

• Steel is basically an alloy of iron and carbon in which the carbon content can be less than 1.7% and carbon is present in the form of iron carbide to impart hardness and strength.
• Two main categories of steel are (a) Plain carbon steel and (b) alloy steel.
• Thus, wrought iron is an iron alloy with a very low carbon (less than 0.08%) content in contrast to cast iron.

Note: The best available option here will be 1.7 to 4.5% for Cast Iron.