As we have mentioned in various articles from Ulbrinox, steel is an alloy composed of Iron (Fe), a small amount of carbon, and other elements in smaller proportions such as silicon, manganese, chromium, among others.
AISI Standard
To name the stainless steels that have more than 10% chromium and less than 1.2% carbon, the American Iron and Steel Institute (AISI) developed a unique nomenclature. This standard establishes three digits and, for certain cases, an alphabetical character.
The first digit indicates the group or series to which the stainless steel belongs according to its crystalline structure, these can be:
2XX: Designates the series of austenitic (austenoferritic) steels to chromium, manganese and nickel (Cr-Mg-Ni).
3XX: Denotes the series of austenitic steels to chromium, molybdenum and nickel (Cr-Mo-Ni).
4XX: Names the series of ferritic and martensitic steels to chromium (Cr).
The following two figures are not related to composition only, they are digits established by the AISI to distinguish the different grades of each series. Depending on the grade, the letter after the third digit indicates that the stainless steel alloy has an additional element or a particular feature.
Types of grades of stainless steel
Stainless steel is commonly classified into five different families, four of which have characteristics of the crystalline structures originated in the alloy: austenite, ferrite, martensite and duplex. The last family is composed of precipitation hardened alloys, they are based on the type of heat treatment used rather than on the crystalline structure.
Given the above, it is of vital importance to have knowledge of the type of stainless steel that is acquired to determine if due to its characteristics and physicochemical properties it will function properly in whatever the objective and/or final product for which the stainless steel was acquired.
At Ulbrinox we have a wide range of each type of steel for your industry, contact us for personalized advice .
