Stainless steel is a family of iron-based alloys containing about 10.5% chromium or more, plus other alloying elements such as nickel, manganese, molybde- num, sulfur, selenium, titanium, etc. The chromium is chiefly responsible for corrosion and heat resistance; the other alloying elements are present in stainless steel to enhance corrosion resistance and to impart certain characteristics with respect to strength and fabric ability.
A total of 60 commercial stainless steel types were originally recognized by the American Iron and Steel Institute (AISI) as standard compositions. A com- plete listing of all stainless steels and a description of each are contained in the SSINA publication, Design Guidelines for the Selection and Use of Stainless Steel.
In addition to the standard AISI types, many special analysis and proprietary stainless steels are produced in the United States and Canada. See more at wholesale fasteners Oklahoma City.
AUSTENITIC stainless steels are chromium-nickel-manganese and chromium-nickel compositions identified by 200 and 300 Series numbers, respec- tively. They can only be hardened by cold work and are non-magnetic in the annealed condition. Typical of the austenitic group is Type 304, which con- tains nominally 18% chromium and 8% nickel; hence the 18-8 name.
FERRITIC stainless steels are straight- chromium steels in the 400 Series that are not hardenable by heat treatment and only slightly hardenable by cold working. All are magnetic. Type 430 is typical of this group.