Alloy 303 is a non-magnetic, austenitic stainless steel that is not hardenable by heat treatment. It is the free machining modification of the basic 18% chromium / 8% nickel stainless steel. Alloy 303 was specially designed to exhibit improved machinability while maintaining good mechanical and corrosion resistant properties Due to the presence of sulphur in the steel composition, Alloy 303 is the most readily machineable austenitic stainless steel; however, the sulphur addition does lower Alloy 303’s corrosion resistance to below that of Alloy 304. Like other austenitic grades, Alloy 303 demonstrates excellent toughness, although the sulphur does reduce this a little as well.
Alloy 303 is frequently used in applications that require parts to be heavily machined. Some examples include: