Phase Diagrams

· The microstructure produced by the equilibrium cooling of an alloy with less than the eutectoid carbon content, a hypo-eutectoid steel, will have pro-eutectoid Ferrite and a perlitic grain structure as shown.
· The generation of the hypo-eutectoid structure during the phase transition is illustrated.
· Prior to reaching the eutectoid temperature, the alloy enters the two-phase γ + α zone. Cooling to the eutectoid temperature, Ferrite crystals grow in the Austenite matrix, and the γ-Fe increases in carbon content until the eutectoid temperature is reached.

From: Callister, "Materials Science and
Engineering," Wiley (1994)