In the equilibrium iron–carbon diagram, eutectoid temperature and composition are 727°C and 0.77 wt% C. A 1.2 wt% C steel cools from 1000°C to room temperature. Find pro-eutectoid cementite fraction (two decimals).
Just above eutectoid temperature, use the lever rule between austenite at 0.77% C and cementite at approximately 6.67% C: $f_{cem}=(1.20-0.77)/(6.67-0.77)=0.07288$. This is the pro-eutectoid constituent; the remaining austenite becomes pearlite. Rounded fraction: **0.07, A**.
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