Iron carbon Phase Diagram 2

All iron-carbon alloys (steels and cast irons) experience eutectoid transformation at 1333 oF (723oC). The eutectoid concentration of carbon i

0.83%. When the temperature of an alloy reaches 1333 oF (733oC), austenite

transforms to pearlite (fine ferrite-cementite structure, forming as a result of decomposition of austenite at slow cooling conditions).

Hypoeutectoid steels (carbon content from 0 to 0.83%) consist of primary (proeutectoid) ferrite (according to the curve A3) and pearlite. Eutectoid steel (carbon content 0.83%) entirely consists of pearlite.

Hypereutectoid steels (carbon content from 0.83 to 2.06%) consist of primary (proeutectoid)cementite (according to the curve ACM) and pearlite.

Cast irons (carbon content from 2.06% to 4.3%) consist of proeutectoid

cementite C2 ejected from austenite according to the curve ACM ,

pearlite and transformed ledeburite (ledeburite in which austenite

transformed to pearlite).s