Austenite

Definition - What does Austenite mean?

Austenite is a solid solution of mostly iron and carbon. It has a face-centered cubic crystal structure. Austenite only forms when an iron-based alloy is heated above about 750°C (1382°F) but not above about 1450°C (2642°F). Austenite keeps its form at room temperature when special alloying elements have been added to the iron-based alloy.

Corrosionpedia explains Austenite

Austenite is probably most commonly known for its presence in austenitic stainless steels. Austenite exists in these stainless steels at room temperature because of their high amounts of nickel. Nickel has special properties that promote the formation of austenite in steel and other iron-based alloys. Other elements, such as chromium, deter the formation of austenite and make it more difficult to form in iron-based alloys. Without high amounts of nickel or another austenite-promoting element, an iron-based alloy will typically form pearlite or ferrite when lowered from the temperatures where austenite normally occurs.

Austenitic stainless steels are mostly non-magnetic even though they have high amounts of iron in them. This is because the face-centered cubic arrangement of its atoms is not magnetic, unlike the body-centered cubic structure that ferrite has. The face-centered cubic structure of austenite also allows it to hold higher amounts of carbon than other steel crystal structures.

Austenite was named in honor Sir William Chandler Roberts-Austen, who created the first iron-carbon phase diagram in the 19th century.


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