Austenitic steel includes up to 0.15% of carbon and minimum 16% of chromium. At least 6% of nickel is also an important additive, because in combination with other elements, it provides the steel with good resistance to corrosion, permanent austenitic structure that is kept at all temperatures. The higher content of alloying additives, such as chromium and molybdenum, the better resistance to corrosion. The greatest global demand for austenitic stainless steels is now being observed on the market. This grade represents about 70% of the total stainless steel production. Properties that make austenite so popular are the highest resistance to corrosion, good ability to plastic deformations, ductility and weldability. They have a single-phase structure that creates the best conditions for passive condition to occur and for its maintenance.
The most popular alloys include 18% of chromium and 10% of nickel, commonly known as 18/10.
Super austenitic stainless steel has higher content of alloying elements and shows improved resistance in aggressive environment. Typical example is an alloy such as 904L or 254SMO, which because of high content of molybdenum (over 4% and over 6%), nickel and addition of nitrogen shows great resistance to chlorides causing pit corrosion.
Austenitic steel is mostly used in high temperature and humidity environment, where it is subjected to high mechanical loads and other aggressive conditions. It is used in chemical and petrochemical industry, aviation, railway and ship building industry, civil engineering and household equipment sector.
The most popular and commonly available austenitic steel grades are as follows: EN 1.4301/1.4307 (AISI 304/304L) and EN 1.4401/1.4404 (AISI 316/316L).
Type 304L is a grade of lower carbon content than 304 and it is adapted to severe corrosive environment. Type 304H can however be characterized by higher carbon content than the remaining versions and can be applied in high temperature environments.
Steels of this group are non-magnetic. They characterize with easy production, cleaning and have aesthetic appearance. High chromium content makes the material very resistant to impact of corrosive and oxidizing factors. Because of its perfect forming properties and weldability, this grade is used in many sectors of industry.
The grade 304 is commonly used in food industry due to its chemical inertia in contact with food products as well as in contact with product cleaning detergents. It is not susceptible to corrosion in the presence of acids present in food products. The described steel grade is used in the following fields: storage and treatment of food products, delivery of food, storage tanks, brewery components, gastronomy premises equipment, devices and commercial kitchen utensils. The steel is also designed for hospital equipment and chemical engineering instrumentation. This grade is also used for building heat exchangers, chemical tanks, pipelines or for application in brewing industry.