The steel is common throughout industry particularly in food processing as the material is not susceptible to corrosion from acids found in common foodstuffs. As a consequence, such steel is ideal for items such as sinks, work surfaces, preparation areas and refrigerators. It is also a perfect material for use in the pharmaceutical industry for environments such as clean rooms.

Grade 321 can also be found in heat exchangers, chemical containers, pipelines and throughout the brewing industry. It can be used as a fabricated material where high temperature petroleum gases or steam production gases are stored such as pressure vessels. It can even be found extensively in the construction industry where the material is used for cosmetic purposes such as building fascias.

321 plate and pipes have similar properties and in certain cases are stocked with Dual Certification, where it is concluded that each item has properties and a composition which comply with both steel types. Grade 321H cannot be included in this equation due to the steel's higher carbon content which is intended for use in elevated temperature applications.

These comparisons are approximate only. The list is intended as a comparison of functionally similar materials not as a schedule of contractual equivalents. If exact equivalents are needed original specifications must be consulted.

Excellent in a wide range of atmospheric environments and many corrosive media. Subject to pitting and crevice corrosion in warm chloride environments, and to stress corrosion cracking above about 600C. Considered resistant to potable water with up to about 200mg/L chlorides at ambient temperatures, reducing to about 150mg/L at 600C.

Good oxidation resistance in intermittent service to 8700C and in continuous service to 9250C. Continuous use of 321 in the 425-8600C range is not recommended if subsequent aqueous corrosion resistance is important. Grade 321 is more resistant to carbide precipitation and can be heated into the above temperature range.

Grade 321H has higher strength at elevated temperatures so is often used for structural and pressure-containing applications at temperatures above about 5000C and up to about 8000C. 321H will become sensitised in the temperature range of 425-8600C; this is not a problem for high temperature applications, but will result in reduced aqueous corrosion resistance.