304/304L Stainless Steel Sheet
High strength, excellent corrosion resistance and excellent formability make Types 304 and 304L useful for many applications. Typical uses include architectural moldings and trim, kitchen equipment, as well as chemical, textile, paper, and pharmaceutical industry processing equipment. For severely corrosive environments or when welding is required, Type 304L is preferred because of its greater immunity to intergranular corrosion.
Chemical Composition(%)
| Composition | Type 304 | Type 304L |
| Carbon (C) | 0.08 max. | 0.03 max |
| Manganese (Mn) | 2.00 max. | 2.00 max |
| Phosphorus (P) | 0.045 max. | 0.045 max. |
| Sulfur (S) | 0.030 max. | 0.030 max. |
| Silicon (Si) | 0.75 max. | 0.75 max. |
| Chromium (Cr) | 18.0 – 20.00 | 18.0 – 20.00 |
| Nickel (Ni) | 8.00 – 12.00 | 8.00 – 12.00 |
| Nitrogen (N) | 0.10 max. | 0.10 max. |
| Iron (Fe) | Balance | Balance |
Mechanical Properties
| Grade | UTS, ksi. (MPa) | 0.2% YS, ksi. (MPa) | Elongation % in 2″ (50.8 mm) | Rockwell Hardness, B |
| 304 | 95 (655) | 42 (290) | 55 | 84 |
| 304L | 95 (655) 40 (276) 55 82 | 40 (276) | 55 | 82 |
Physical Properties
| Density, lbs./in.3 (g/cm3) | 0.29 (8.03) |
| Electrical Resistivity, µΩ•in. (µΩ•cm) 68 °F (20 °C) 1200 °F (659 °C) | 28.4 (72) 45.8 (116) |
| Thermal Conductivity, BTU/hr./ft./°F W/(m•K) 212 °F (100 °C) 932 °F (500 °C) | 9.4 (16.2) 12.4 (21.4) |
| Coefficient of Thermal Expansion, in./in./°F (µm/m/K) 32 – 212 °F (0 – 100 °C) 32 – 600 °F (0 – 315 °C) 32 – 1000 °F (0 – 538 °C) 32 – 1200 °F (0 – 649 °C) | 9.4 x 10-6 (16.9) 9.9 x 10-6 (17.3) 10.2 x 10-6 (18.4) 10.4 x 10-6 (18.7) |
| Modulus of Elasticity, ksi. (MPa) in tension in torsion | 28.0 x 103 (193 x 103) 11.2 x 103 (78 x 103) |
| Magnetic Permeability Annealed, (H/m at 200 Oersteds | 1.02 max |
| Specific Heat, BTU/lbs./°F (kJ/kg/K) 32 – 212 °F (0 – 100 °C) | 0.12 (0.50) |
| Melting Range, °F (°C) | 2550 – 2650 (1399 – 1454) |
Characteristics
Corrosion Resistance
Types 304 and 304L exhibit excellent resistance to corrosive environments such as the chemical, textile and petroleum industries. Type 304 and 304L are found suitable in the food and dairy industries as well as excelling in rural and industrial atmospheric exposure. By reducing the carbon content in Type 304L, welding operations will not cause carbide precipitation that can lead to intergranular corrosion.
Oxidation Resistance
The maximum temperature to which Type 304 can be exposed continuously without appreciable scaling is about 1650 °F (899 °C). For intermittent cyclic exposure, is about 1500 °F (816 °C).
Heat Treatment
Type 304 is non-hardenable by heat treatment. Annealing: Heat to 1900 – 2050 °F (1038 – 1121 °C), then cool rapidly.
Thin strip sections may be air cooled, but heavy sections should be water quenched to minimize exposure in the carbide precipitation region. Stress Relief Annealing: Cold worked parts should be stress relieved at
750 °F (399 °C) for 1/2 to 2 hours.
Cold Working
High hardness and strength are achieved through cold working. In the annealed condition, Types 304 and 304L are very ductile and can be cold worked easily by roll forming, deep drawing, bending, and other common fabricating methods. Since the material work hardens rapidly, in-process annealing may be necessary to restore ductility and to lower hardness.
Formability
Types 304 and 304L can be readily formed and drawn. The higher nickel versions of Type 304 are well suited to severe forming
applications involving multi-draw operations and forming of complex shapes. This is largely due to its combination of lower strength and lower work hardening rate. As with all austenitic stainless steels, annealing or stress-relieving can be performed following fabrication.
Weldability
The austenitic class of stainless steels is generally considered to be weldable by the common fusion and resistance techniques. Special consideration is required to avoid weld “hot cracking” by assuring formation of ferrite in the weld deposit. Types 304 and 304L are generally considered to be the most common alloys of this stainless class. When a weld filler is needed, AWS E/ER 308, 308L or 347 are most often specified.
