SS304 Stainless Steel
SS304 is a widely used austenitic chromium-nickel stainless steel combining corrosion resistance, mechanical strength, formability and weldability for general industrial sealing service.
SS304 Grade Information
SS304, commonly designated AISI 304, is an austenitic chromium-nickel stainless steel. Chromium is the principal alloying element responsible for formation of the protective passive surface layer, while nickel stabilizes the austenitic structure.
For Spiral Wound Gaskets, SS304 may be used as metallic winding material and for compatible ring components where the process medium, operating temperature and service environment are suitable for this grade.
| Common Designation | SS304 / AISI 304 |
|---|---|
| UNS Number | S30400 |
| EN / Werkstoff | 1.4301 / X5CrNi18-10 |
| Material Family | Austenitic chromium-nickel stainless steel |
| Common Specification | ASTM A240 / A240M |
| Typical Gasket Use | Metallic winding and compatible ring components |
SS304 Chemical Composition
Typical composition limits for SS304 under ASTM A240 / A240M. Exact chemistry must be confirmed from the applicable specification and material certificate.
| Element | Symbol | Composition, % |
|---|---|---|
| Carbon | C | 0.08 max. |
| Manganese | Mn | 2.00 max. |
| Silicon | Si | 0.75 max. |
| Phosphorus | P | 0.045 max. |
| Sulfur | S | 0.030 max. |
| Chromium | Cr | 18.00 – 20.00 |
| Nickel | Ni | 8.00 – 10.50 |
| Nitrogen | N | 0.10 max. |
| Iron | Fe | Balance |
SS304 Mechanical Properties
Representative minimum mechanical requirements for annealed SS304 sheet and strip. Requirements vary with product form, thickness, condition and governing material specification.
| Property | Requirement | Unit |
|---|---|---|
| Tensile Strength | 515 min. | MPa |
| 0.2% Offset Yield Strength | 205 min. | MPa |
| Elongation | 40 min. | % |
| Brinell Hardness | 201 max. | HBW |
| Rockwell B Hardness | 92 max. | HRB |
Mechanical values shown are reference requirements, not design allowables. Use the governing material standard and certified material test report for final engineering and procurement.
SS304 Physical & Service Information
Reference physical properties and service considerations relevant to material selection.
| Density | Approximately 8.0 g/cm³ |
|---|---|
| Elastic Modulus | Approximately 193 GPa |
| Thermal Conductivity | Approximately 16 W/m·K near 100°C |
| Mean Thermal Expansion | Approximately 17.2 µm/m·K from 20–100°C |
| Melting Range | Approximately 1400–1450°C |
| Structure | Austenitic |
| Magnetic Behaviour | Generally non-magnetic in the annealed condition; cold working can introduce some magnetic response |
| Corrosion Behaviour | Good resistance in many general environments. Chloride-rich conditions can cause pitting or crevice corrosion and may require a more resistant grade |
| Heat Treatment | Normally supplied solution annealed. Final treatment requirements depend on product form and specification |
| Spiral Wound Gasket Selection | Use where SS304 is compatible with the process medium, operating temperature, pressure and selected filler material |
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