ATI 302™ (S30200), ATI 304™ (S30400), ATI 304L™ (S30403), and ATI 305™ (S30500) stainless steels are variations of the 18 percent chromium - 8 percent nickel austenitic alloy, the most familiar and most frequently used alloy in the stainless steel family. These alloys may be considered for a wide variety of applications where one or more of the following properties are important:
1. Resistance to corrosion
2. Prevention of product contamination
3. Resistance to oxidation
4. Ease of fabrication
5. Excellent formability
6. Beauty of appearance
7. Ease of cleaning
8. High strength with low weight
9. Good strength and toughness at cryogenic temperatures
10. Ready availability of a wide range of product forms

Each alloy represents an excellent combination of corrosion resistance and fabricability. This combination of properties is the reason for the extensive use of these alloys which represent nearly one half of the total U.S. stainless steel production. ATI 304 alloy represents the largest volume followed by ATI 304L alloy. ATI 302 and ATI 305 alloys are used in smaller quantities. The 18-8 stainless steels, principally ATI 304 and 304L alloys, are available in a wide range of product forms including sheet, strip, foil and plate from Allegheny Ludlum. The alloys are covered by a variety of specifications and codes relating to, or regulating, construction or use of equipment manufactured from these alloys for specific conditions. Food and beverage, sanitary, cryogenic, and pressure-containing applications are examples.

Past users of ATI 302 stainless are generally now using ATI 304 alloy since AOD technology has made lower carbon levels more easily attainable and economical. There are instances, such as in temper rolled products, when ATI 302 alloy is preferred over ATI 304 since the higher carbon permits meeting of yield and tensile strength requirements while maintaining a higher level of ductility (elongation) versus that of the lower carbon T304. ATI 304L alloy is used for welded products which might be exposed to conditions which could cause intergranular corrosion in service. ATI 305 alloy is used for applications requiring a low rate of work hardening during severe cold forming operations such as deep drawing.

Other less frequently specified 18-8 stainless steel grades, such as ATI 304N (S30451) and ATI 304LN (S30453) alloys are also available from Allegheny Ludlum.