Which carbon content category is associated with ferrite and pearlite microstructure?

Which carbon content category is associated with ferrite and pearlite microstructure?

• A. Less than 0.83% carbon
• B. Greater than 1.0% carbon
• C. Between 0.83% and 1.0% carbon
• D. Exactly 0.83% carbon

Answer: (A)

In steels, the carbon content determines which phases appear after cooling. Ferrite is essentially iron with very little carbon, and pearlite is a lamellar mix of ferrite and cementite formed when austenite transforms at the eutectoid temperature. In steels with carbon content below the eutectoid range (roughly under 0.8% C, often cited as about 0.83%), the microstructure develops as proeutectoid ferrite plus pearlite. That’s why ferrite and pearlite are associated with carbon contents less than about 0.83%. If the carbon were higher, you’d expect more cementite-rich structures (hyper-eutectoid) rather than a ferrite-plus-pearlite mix.

In steels, the carbon content determines which phases appear after cooling. Ferrite is essentially iron with very little carbon, and pearlite is a lamellar mix of ferrite and cementite formed when austenite transforms at the eutectoid temperature. In steels with carbon content below the eutectoid range (roughly under 0.8% C, often cited as about 0.83%), the microstructure develops as proeutectoid ferrite plus pearlite. That’s why ferrite and pearlite are associated with carbon contents less than about 0.83%. If the carbon were higher, you’d expect more cementite-rich structures (hyper-eutectoid) rather than a ferrite-plus-pearlite mix.