What Does
Austenitic Mean?
Austenitic refers to an alloy consisting mainly of austenite. The most widely used grade of stainless steel is austenitic. Austenitic alloys contain a high percentage of nickel and chromium, which makes them, and the steel made from them, very resistant to corrosion.
Austenitic stainless steels are used in a wide range of applications, including:
- Automotive trim
- Aircraft
- Cookware
- Food and beverage equipment
- Industrial equipment
Austenitic stainless steels have also been used in conventional and nuclear power plants’ superheaters and heating components.
Corrosionpedia Explains Austenitic
Stainless steels can be classified by their crystalline structure into three main types:
- Austenitic
- Ferritic
- Martensitic
Austenitic steels have austenite as their primary phase. These alloys contain chromium and nickel, and sometimes manganese and nitrogen. Austenitic steels, which contain 16 to 26 percent chromium and up to 35 percent nickel, usually have the highest corrosion resistance. The most common type is the 18/8 or 304 grade, which contains 18 percent chromium and 8 percent nickel.
Austenitic steels are non-magnetic in the annealed condition, although they can become slightly magnetic when cold worked. They are not hardenable by heat treatment. They have good formability and weldability, as well as excellent toughness, particularly at low or cryogenic temperatures. Austenitic grades also have a low yield stress and relatively high tensile strength.
When compared to a typical carbon steel, austenitic stainless steels have:
- High ductility
- Low yield stress
- High ultimate tensile strength
Austenitic steels are not susceptible to hydrogen cracking, therefore pre-heating is seldom required, except to reduce the risk of shrinkage stresses in thick sections. Post-weld heat treatment is seldom required, as this material has a high resistance to brittle fracture. Occasionally stress relief is carried out to reduce the risk of stress corrosion cracking, however this is likely to cause sensitization unless a stabilized grade is used.