AISI 303

What is 303 Steel? 

AISI 303 (in accordance with ASTM A582/A582M-12, AISI / SAE 303, DIN 1.4305 and JIS SUS 303), is an austenitic stainless steel hardenable by mechanical work, it is classified as a member of the "Free Machining Stainless Steel" family of steels. » due to its high sulfur and phosphorus contents, which significantly improve its machinability.

Regarding its chemical composition, it has a maximum of 0.15% carbon, a maximum of 2.00% manganese, a maximum of 0.20% phosphorus, a minimum of 0.15% sulfur, a maximum of 1.0% silicon, and a range of 17.0% to 19.0% chromium and 8.0% to 10.0% nickel, supplied in an annealed state, reaching a maximum hardness of 303 stainless steel of 262 HB (~26 HRC).

In terms of mechanical properties at room temperature, it has a tensile strength of 618 MPa (63,000^Lb/in²), yield strength of 225 MPa (23,000^Lb/in²), elongation of 50%, area reduction of 55%, these values ​​are typical in annealed conditions and should be taken as a general reference according to the NMX – B- 83 – 1988 standard. Characterized by being non-magnetic in the annealed state, the AISI 303 can acquire some magnetization during forming processes such as machining or cold deformation, its high machinability is due to the sulfur and phosphorus contents, but this results in a decrease in its hot forgeability, making it prone to cracks during rolling.

In addition to its good corrosion resistance, AISI 303 stands out for its lower thermal conductivity (approximately 50%), compared to carbon, low alloy or tool grade steels, in terms of applications, it is used in mass production. of mechanical parts exposed to corrosive environments, such as screws, bushings, couplings and connections, can be considered as a substitute for AISI 304 (AISI 303 vs 304), although with a slight reduction in its corrosion resistance, it can also replace AISI /SAE 304 (lower machinability).