Austenitic stainless steels are Iron-Carbon-Chrome-Nickel alloys with the possible addition of other elements such as Molybdenum, Titanium and Niobium in such percentages as to maintain the austenitic structure even at room temperature; considering the considerable percentage of valuable components (Ni, Cr, Mo, Ti, Nb), austenitic stainless steels are among the most expensive of steels in common use.

In the AISI classification they are identified as the 300 series and the various grades of this family differ mainly in their nickel content; the basic composition of austenitic stainless steel is 18% chrome and 8% nickel, codified as AISI 304, or 18/8, while adding a percentage of 2-3% of molybdenum ensures better corrosion resistance and results in AISI 316, or 18/10.

In austenitic steels, the Carbon content is low, around 0.08% maximum, but there are also austenitic stainless steels with a Carbon content of 0.03% maximum which are called soft austenitic steels and are defined by a final L in the abbreviation, such as AISI 304L or 316L (Low Carbon).

Austenitic steels have a crystalline structure with a face-centred cubic lattice (CFC).