Austenitic Stainless Steel

Austenitic Stainless Steel

As the most common type of stainless steel, austenitic stainless steel has the highest ratio of chromium and can be used in mild, harsh and corrosive environments. Accounting for 70% of the total stainless steel production, the term "austenitic" refers to the crystalline structure of the stainless steel which allows for higher ductility, tensile strength and lower yield stress than typical carbon-based steels. Also referred to as 300 series stainless steels, austenitic stainless steels are non-magnetic and provide excellent mechanical properties. Although they can not be hardened through heat treatment, austenitic stainless steel can be significantly hardened through cold working. As the most readily formed type of stainless steel, austenitic stainless steel offers excellent welding and forming characteristics. Pre-heating is seldom required for austenitic stainless steels, and typical applications include pipe fittings, food processing equipment, chemical tanks, ovens, heat exchangers, roofing, gutters and cladding. As a result of the wide range of applications, austenitic stainless steel is used in many industries including marine, manufacturing, plumbing, food and chemical processing, aerospace, automotive, construction, chemical and pharmaceutical. Additional advantages of austenitic stainless steel include high ductility and excellent toughness.

Austenitic stainless steel typically consists of at least 16% chromium and 6% nickel. In addition, the carbon content of the steel must be less than or equal to .1%. There are many different grades of austenitic stainless steel, although the main types are straight grades, L-grades and H-grades. Straight grades of austenitic stainless steel contain a maximum of .08% carbon and include the following types: 304, 316, 317, 321 and 347. L-grades of austenitic stainless steel require an even lower amount of carbon, with a maximum of just .03%. L-grades are use for increased weldability; however, they are often more expensive and is feature decreased tensile strength versus straight or H-grade austenitic stainless steel. Common types of L-grade austenitic stainless steel include 304L, 316L and 317L. H-grades of austenitic stainless steel offer the highest carbon content with a minimum of .04% and a maximum of .10%. H-grades are typically used for application requiring higher tensile strength because the high carbon content allows the metal to retain its strength at high temperatures. Typical types of H-grade austenitic stainless steel include 304H and 316H, with less common types such as 309H, 310H, 321H, 347H and 348H also available.