Austenitina

Austenitina is a term that is sometimes used to describe austenite, the gamma-iron phase of the iron–carbon system. In this context, it refers to the solid solution of carbon in face-centered cubic iron (gamma-iron). Austenite is typically paramagnetic and, at elevated temperatures, can dissolve relatively large amounts of carbon compared with ferrite.

The structure of austenite is face-centered cubic, which provides higher symmetry and greater solubility for carbon than the body-centered cubic structure of ferrite. In steels and cast irons, austenite forms when the material is heated above characteristic austenitizing temperatures, often near and above the Ac1 and Ac3 transformations, depending on carbon content and alloying. Alloying elements such as nickel, manganese, nitrogen, and certain others stabilize austenite and can allow it to persist to room temperature in some stainless steels and high-nitrogen steels.

Formation, stability, and transformations are central to heat treatment and alloy design. Upon cooling, austenite can transform to ferrite and cementite to form pearlite in eutectoid steel, or it can transform into bainite or martensite depending on the cooling rate and composition. In alloyed steels, particularly austenitic stainless steels, nickel and other stabilizers keep the gamma-iron phase stable at ambient conditions, imparting high ductility and corrosion resistance.

Notes: the standard term in modern literature is austenite; austenitina may appear in some regional or historical usages. The article uses austenite as the primary term while acknowledging the alternate usage.