Types 302, 304, 304L & 305 Stainless Steel

General Properties

Types 302, 304, 304L and 305 are variations of the 18 percent chromium – 8 percent nickel austenitic alloy, the most familiar and most frequently used members of the stainless steel family. Together they account for nearly half of U.S. stainless production, with Type 304 the largest by volume followed by 304L; 302 and 305 are used in smaller quantities.

Consider these alloys when one or more of the following matter:

• Corrosion and oxidation resistance
• Prevention of product contamination
• Ease of fabrication and excellent formability
• Appearance and ease of cleaning
• High strength with low weight
• Strength and toughness at cryogenic temperatures

Food and beverage, sanitary, cryogenic and pressure-containing equipment are typical applications.

Chemical Composition

Mechanical Properties

Physical Properties

Annealed condition, average composition. *The modulus is lowered in the cold-worked condition.

Thermal Expansion

Thermal Conductivity

Overall heat transfer depends on more than the conductivity of the metal. Because the austenitic stainless grades keep their surfaces clean, they often transfer heat better in service than metals with higher thermal conductivity.

Electrical Resistivity

Corrosion Resistance

These grades resist a wide range of moderately oxidizing to moderately reducing environments. They are used extensively for food, beverage and dairy processing equipment; heat exchangers, piping and tanks in fresh water; architectural applications in non-marine atmospheres; and handling of many household and industrial chemicals.

Intergranular Corrosion

Exposure to 800–1500 °F (427–816 °C) can precipitate chromium carbides at grain boundaries (“sensitization”), leaving the steel open to intergranular attack in aggressive environments. Low-carbon Type 304L is preferred for parts placed in service as-welded. Its low carbon delays — but does not eliminate — carbide precipitation during long exposure in that range.