303 Stainless also considered ”free machining stainless” is for use in automatic machining operations. Corrosion resistant to atmospheric exposures, sterlizing solutions, most organic and many inorganic chemicals.

This material is not as resistant to general corrosion as is 304. It tends to form a rust film more readily in moist atmospheres and is very susceptible to pitting or localized corrosion in solutions of chlorides, iodides, or bromides. Under relatively dry conditions or in mildly corrosive environments, 303 resists rust. It also has good resistance to oxidation up to 1700°F. 303 is not recommended for vessels containing gases or liquids under high pressure. It is available as hot rolled, annealed and pickled (HRAP) or hot rolled, annealed only (HRA) plate.