Phase Diagrams II: Phase Diagrams II: The Iron- Iron The Iron- Iron

Carbide DiagramCarbide Diagram

Objectives

1. Explain and use the terms hypoeutectoid, hypereutectoid, proeutectoid, and pearlite.

2. Identify the major phases on the F-C diagram and explain their chief characteristics.

3. Identify the proeutectoid phase for a given alloy.

The Iron-Carbon The Iron-Carbon DiagramDiagram

Callister, Materials Science and Engineering An Introduction, John Wiley & Sons

General Properties:

Ferrite - Iron with a little Carbon. Fairly Soft.

Austenite - FCC Iron with much Carbon.Ductile.

Cementite - Hard ceramic material.

Hypoecutectoid Line a-e; Cool From a to d.

Proeutectoid – Forms before eutectoid

Eutectoid Steel

NO Proeutectoid phase!

Pearlite

Ferrite (white)

Cementite (dark)

Eutectoid Steel Eutectoid Steel

Proeutectoid Cementite

(white)

Pearlite (striped)

Hypereutectoid SteelHypereutectoid Steel

Effects of Carbon Effects of Carbon ContentContent