GATE 2021 MT – Question 32
Steel containing 0.6 wt.% C is cooled slowly from 900 °C to room temperature. The proeutectoid ferrite fraction is ______ (two decimal places). Given eutectoid composition 0.8 wt.% C and maximum carbon solubility in α-Fe 0.025 wt.% C.
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Correct answer: 0.22 to 0.30
Explanation
At the eutectoid temperature, apply the lever rule between ferrite 0.025 wt.% C and austenite 0.8 wt.% C. Ferrite fraction is (0.8−0.6)/(0.8−0.025)=0.25806, or **0.26**.