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Ferrite and pearlite in high strength steel

Short answer

Assuming high‑strength steel is eutectoid (0.80% C): pearlite = 100%; lamellar ferrite inside pearlite = 88.01%; cementite = 11.99%; free proeutectoid ferrite = 0%. The structure is entirely pearlite.

What is the percentage of ferrite and pearlite in high strength steel?

The question gives no carbon content, so the common textbook case is taken: high strength steel is high carbon steel of eutectoid composition, 0.80% C. Pearlite holds 0.80% C and cementite holds 6.67% C (carbon dissolved in ferrite is neglected).

Pearlite=0.800.80×100=100%\text{Pearlite} = \frac{0.80}{0.80} \times 100 = 100\% Cementite=0.806.67×100=11.99%,Ferrite=100−11.99=88.01%\text{Cementite} = \frac{0.80}{6.67} \times 100 = 11.99\%, \qquad \text{Ferrite} = 100 - 11.99 = 88.01\%

So the structure is 100% pearlite, made of about 88% ferrite and 12% cementite layers. Free ferrite is zero.

General method for any hypo-eutectoid steel with carbon CC (%): pearlite =C0.80×100= \dfrac{C}{0.80} \times 100 and free ferrite =100−= 100 - pearlite. For example, for 0.60% C: pearlite =75%= 75\%, free ferrite =25%= 25\%.

Answer: Pearlite = 100%, with 88.01% ferrite and 11.99% cementite inside it (0.80% C steel).

✓ Answer checked by Claude Opus 5.5 (high effort)

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