Iron-Carbon Phase Diagram Explorer
Explore the metastable Fe–Fe₃C iron-carbon phase diagram. Select a carbon concentration and temperature to identify the approximate phase region and understand important transformation temperatures.
Fe–Fe₃C Phase Diagram
Carbon content in wt% C
Critical Transformation Points
Eutectoid
Austenite transforms into ferrite + cementite.
Eutectic
Liquid transforms into austenite + cementite.
Max α-C Solubility
Maximum carbon solubility in ferrite.
Max γ-C Solubility
Maximum carbon solubility in austenite.
Engineering Interpretation
Ferrite (α)
Body-centered cubic iron phase stable at lower temperatures. It has relatively low carbon solubility and generally provides good ductility and toughness.
Austenite (γ)
Face-centered cubic phase capable of dissolving significantly more carbon than ferrite. Austenite is central to steel heat-treatment processes.
Cementite (Fe₃C)
Iron carbide containing approximately 6.67 wt% carbon. It is hard and brittle and strongly influences the hardness and wear resistance of steels.
Pearlite
A lamellar microstructural mixture of ferrite and cementite formed from eutectoid austenite during slow cooling.
Frequently Asked Questions
What is the eutectoid composition of steel?
The eutectoid composition in the metastable iron-carbon system occurs at approximately 0.76 wt% Carbon at 727 °C, where austenite transforms completely into pearlite (ferrite + cementite).
What is the difference between Austenite and Ferrite?
Austenite (γ) is a face-centered cubic phase capable of dissolving significantly more carbon than Ferrite (α), which is a body-centered cubic phase stable at lower temperatures with very low carbon solubility.
Scope: This tool represents the metastable Fe–Fe₃C system commonly used for steel and cast-iron engineering education. Real alloys may contain additional elements such as Mn, Si, Cr, Ni and Mo, which can shift phase boundaries and transformation temperatures.