Austenitic stainless steels
Technical data sheets for austenitic stainless steel grades
Austenitic stainless steels have an austenitic structure at any temperature, as unlike martensitic steels, the austenitic steels are not hardenable by heat treatment as no phase changes occur on heating or cooling. Because of their austenitic structure austenitic stainless steels exhibit superior corrosion resistance to both ferritic and martensitic stainless steels. Corrosion performance may be varied to suit a wide range of service environments by careful alloy adjustment. Austenitic stainless steel deformation behaviour (such as cold drawing) can withstand reduction values (up to 80%) and reach tensile strength higher than 2000 MPa. Austenitic stainless steels are often described as non-magnetic, but may become slightly magnetic when machined or worked. Despite some of the alloys, such as grades 304 and 316, contain iron, these materials are non-ferromagnetic. Austenitic stainless steels are often described as non-magnetic, but may become slightly magnetic when machined or worked. The main alloying elements of this category of stainless steels are chromium and nickel. Grade 304 is the most versatile and most widely used stainless steel available, also known as 18-10, an acronym that identifies the average percentage of chromium and nickel. Grade 304L it is a low carbon version, where L stands for Low carbon. Austenitic steel has a series of variants, including 316, which differs in the presence of molybdenum and a higher percentage of nickel, used in chloride environments, such as marine environments. While the presence of the sulphur in grade 303, makes it suitable for chip removal.
The group of austenitic stainless steels represents the smallest family of commercially available stainless steels. This group of steels has the great advantage of being highly resistant to aggressive environmental conditions, especially corrosion. The austenitic structure and relative high ductility result in exceptional toughness, even at low temperatures. However, its unsurpassed strength makes austenitic steel unsuitable for chip removal.
High nickel content of austenitic steel grades has the following properties:
- High corrosion resistance compared to nickel-free chromium steel (especially against stress corrosion cracking)
- Low yield strength (200–300 N/mm²)
- High tensile strength (700–1300 N/mm²)
- High thermal expansion coefficient (16.0 × 10−6 K−1 for material 1.4301)
- Density 1.4301 (V2A, AISI 304): 7.9 g/cm3, 1.4401 (V4A, AISI 316L): 8.0 g/cm3. Austenitic steel cannot be hardened by heat treatment
- Readily welded
The characteristics of stainless steel are in demand in industry, medical and dental technology, the automotive sector, construction and the chemical industry.
With its exceptional resistance to heat and corrosion, it’s used extensively in many industries including medical, automotive, aerospace, and industrial applications. However, the relatively low hardness and cold welding are limiting factors in many applications.