austenitic

An austenitic material is one whose structure is based on austenite, the face-centered cubic (FCC) phase of iron known as gamma iron. In steel and cast iron, austenite is stable at high temperatures, and in many alloys it can be retained at room temperature by alloying with sufficient nickel or other stabilizers, yielding a structure described as austenitic.

Commonly encountered as austenitic stainless steels, such as the 300-series (for example, 304 and 316), these alloys typically contain nickel, chromium, and sometimes molybdenum, making them highly ductile and non-magnetic in the annealed state. Other austenitic materials include austenitic manganese steels (Hadfield steel), which achieve their properties through high manganese content and remain austenitic at room temperature.

Compared with ferritic or martensitic stainless steels, austenitic grades offer superior formability, toughness, and corrosion resistance in many environments, but they cannot be hardened through conventional heat treatment; strength is typically increased by cold working, alloying, or grain refinement. They may be susceptible to sensitization and chromium carbide precipitation if exposed to certain temperature ranges, which can reduce corrosion resistance.

Applications span chemical processing equipment, food processing, pharmaceutical containers, architectural and consumer products, and cryogenic vessels, where ductility and resistance to stress corrosion cracking are valued. The term austenitic thus describes both the phase present at operating temperatures and the stabilized, room-temperature structure in certain nickel-containing steels and alloys.