Austenite

v • d • e alloy phases
Austenite (γ-iron; hard) Bainite Martensite Cementite (iron carbide; Fe₃C) Ledeburite (ferrite - cementite eutectic, 4.3% carbon) Ferrite (α-iron, δ-iron; soft) Pearlite (88% ferrite, 12% cementite) Spheroidite
Types of Steel
Plain-carbon steel (up to 2.1% carbon) Stainless steel (alloy with chromium) HSLA steel (high strength low alloy) Tool steel (very hard; heat-treated)
Other Iron-based materials
Cast iron (>2.1% carbon) Wrought iron (almost no carbon) Ductile iron

Austenite (or gamma phase iron) is a metallic non-magnetic solid solution of steel have different eutectoid temperatures. It is named after Sir William Chandler Roberts-Austen (1843-1902).

Behavior in Plain-Carbon Steel

As austenite cools, it often transforms into a mixture of tempering will transform some of the brittle martensite into bainite. If a low-hardenability steel is quenched, a significant amount of austenite will be retained in the microstructure.

Stabilization

The addition of certain alloying elements, such as chromium tend to de-stabilize austenite, raising the eutectoid temperature.

Austenite transformation and Curie point

In many magnetic alloys, the ferromagnetic.

Thermo-optical emission

A blacksmith causes phase changes in the iron-carbon system in order to control the material's mechanical properties, often using the annealing, quenching, and tempering processes. In this context, the color of light emitted by the workpiece is an approximate gauge of temperature, with the transition from red to orange corresponding to the formation of austenite in medium- and high-carbon steel.

Maximum carbon solubility in austenite is 2.03% C at 1420 K (1147 °C).

References

"Physical Metallurgy Principles". Reed-Hill, Robert. 3rd. Edition. PWS Publishing. Boston. 1991.