Type 304 stainless steel is the most widely used austenitic stainless steels. Also known as ’18-8′ stainless owing to its composition, which includes 18 percent chromium and 8 percent nickel, 304 stainless steel possesses great forming and welding properties, as well as excellent corrosion resistance and strength.
Type 304 stainless steel also possesses good drawability, can be formed into a variety of shapes and, unlike type 302 stainless steel, can be used without annealing.
Common applications of type 304 stainless steel include in the food industry; for milk processing, brewing, wine making as well as in fermentation vats, yeast pans and storage tanks. Due to its capability to resist corrosion by several chemicals found in fruits, milk and meat, 304 grade stainless steel is also found in sinks, coffee pots, tabletops, refrigerators and other utensils and cooking appliances. Other areas of application include in architecture, mining equipment, heat exchangers, chemical containers, and in marine nuts, bolts and screws.
Type 304L stainless steel is an extra-low carbon version of the 304 steel alloy. The lesser carbon content in 304L minimizes harmful carbide precipitation as a result of welding. Consequently, 304L can be used ‘as welded’ in severe corrosion environments. Readily fabricated by most cold working methods, 304L may need intermediate annealing to avoid cracking or tearing from drastic deformation. Full annealing should follow any operation to reduce internal stress and optimize corrosion resistance. However, this grade has somewhat lower mechanical properties than the standard 304 grade.
Forging, heading and other hot working should follow uniform heating to 2100-2300 F (1149-1260 C). Rapid cooling is necessary to attain maximum corrosion resistance in finished parts. This alloy does not respond to heat treatment. Cold work will effect an increase in both hardness and strength.