Stainless Steel are iron-base alloys containing a minimum of 10.5 percent chormium. There are fifty seven separate and distinct commercial composition designated by America Iron and Steel Institute as standard types. a complete listing of all standard AISI types and a description of each are contained within the AISI publication, “Steel products Manual- stainless and Heat-Resisting Steels.”
In addition to the standard AISI types, several special-analysis and proprietary stainless steels are made within the u. s. and Canada. several of those ar known in technical literature, like within the ASTM knowledge Series booklet DS forty five.
AISI stainless steels ar known by a system of numbers that are either 200, 300, or 400 Series. additionally, all ar known by the new Unified numbering System (UNS) that has been developed for all commercial metals and rare earths. Special analysis and proprietary alloys might have numbers that resemble AISI type numbers. To avoid confusion, the term “alloy” are going to be employed in this publication in referring to stainless steels apart from the AISI compositions.
The terms austenitic, martensitic, ferritic and precipitation hardening serve to identify classes of stainless steels on the basis of their metallurgical structure. Engineers ought to acknowledge these terms and perceive what they mean, because stainless steels therefore classified tend to have similar characteristics with regard to corrosion resistance, harden ability and fabricability.