ASTM A240 304L (UNS S30403) Stainless Steel
ASTM A240 304L (UNS S30403) Stainless Steel - Low‑Carbon Austenitic Grade for Superior Weldability
304L stainless steel (UNS S30403) is a low‑carbon variant of 304, designed to prevent carbide precipitation during welding and ensure resistance to intergranular corrosion. Ideal for chemical, food, and architectural applications requiring good formability and long‑term durability.
Hot rolling, cold rolling, solution annealing, pickling, descaling, welding, forming
- Phone : +8618037372205
- Email : [email protected]
- WhatsApp: Contact via Whtsapp
- WeChat: +8618037372205
ASTM A240 304L Stainless Steel Introduction
304L (UNS S30403) is an austenitic chromium‑nickel stainless steel defined by ASTM A240 for plate, sheet, and strip. Its maximum carbon content of 0.03% reduces the risk of chromium‑carbide precipitation during welding or high‑temperature service, thereby preserving intergranular corrosion resistance in the as‑welded condition without post‑weld annealing. This makes 304L the preferred grade for welded fabrications and heavy‑section components.
The alloy offers a balanced combination of mechanical strength, ductility, and corrosion resistance in a wide range of environments, including oxidizing acids and atmospheric exposure. Typical tensile strength exceeds 485 MPa, with yield strength around 170 MPa and elongation above 40%, ensuring excellent formability for deep drawing, bending, and rolling operations.
Supplied in the solution‑annealed condition, 304L exhibits a fully austenitic microstructure that is non‑magnetic in the annealed state but may become slightly magnetic after cold working. It is widely used in chemical processing equipment, food and beverage handling systems, pharmaceutical plants, architectural cladding, and heat exchangers. The low carbon content also minimizes sensitization during prolonged exposure to moderate temperatures, extending the service life of components in critical applications.
Although 304L has slightly lower room‑temperature strength than 304, its superior weldability and resistance to grain‑boundary corrosion often make it the material of choice for tanks, piping, and pressure vessels that require extensive joining. It can be readily formed, machined, and polished to meet stringent surface finish requirements.
ASTM A240 304L Stainless Steel Chemical Composition – ASTM A240 304L
The chemical limits for 304L (UNS S30403) per ASTM A240 are designed to produce a stable austenitic structure with low carbon to inhibit sensitization. Nitrogen is limited to maintain formability, while chromium and nickel provide corrosion resistance and austenite stabilization.
| Element | Content (%) | Remarks |
|---|---|---|
| Carbon (C) | ≤0.03 | Low carbon prevents carbide precipitation during welding |
| Manganese (Mn) | ≤2.00 | Deoxidizer; improves hot working |
| Silicon (Si) | ≤0.75 | Residual from deoxidation |
| Phosphorus (P) | ≤0.045 | Element, kept low for ductility |
| Sulfur (S) | ≤0.030 | Element, low for weldability |
| Chromium (Cr) | 18.0 – 20.0 | Primary corrosion resistance element |
| Nickel (Ni) | 8.0 – 12.0 | Stabilizes austenitic phase |
| Nitrogen (N) | ≤0.10 | Controlled for mechanical consistency |
ASTM A240 304L Stainless Steel Thermal and Electrical Properties
The following physical constants are typical for 304L in the annealed condition and provide a basis for engineering calculations. Thermal conductivity, expansion, and electrical resistivity data come from standard material datasheets and are valid for temperatures between 20 °C and 100 °C unless noted otherwise.
| Property | Typical Value | Unit | Conditions |
|---|---|---|---|
| Density (ρ) | 8.0 | g/cm³ | Ambient temperature |
| Elastic Modulus (E) | 193 | GPa | Tension, room temperature |
| Shear Modulus (G) | 77 | GPa | Calculated from E and Poisson ratio |
| Poisson's Ratio (ν) | 0.29 | dimensionless | Room temperature |
| Thermal Expansion (α) | 16.5 | µm/m·°C | 20–100 °C range |
| Thermal Conductivity (λ) | 16.2 | W/m·K | At 100 °C |
| Specific Heat | 500 | J/kg·K | At 20 °C |
| Electrical Resistivity (ρ_e) | 0.72 | µΩ·m | At 20 °C |
ASTM A240 304L Stainless Steel Mechanical Properties – Solution Annealed Condition
Minimum mechanical property requirements for plate, sheet, and strip per ASTM A240. The values apply to material in the solution‑annealed condition. Elongation is measured using a 50 mm (2 in.) gauge length. Hardness values are informative and not mandatory.
| Property | Value | Unit | Test Condition |
|---|---|---|---|
| Tensile Strength (Rm) | ≥ 485 | MPa | Transverse, room temperature |
| Yield Strength (0.2 % offset) (ReH) | ≥ 170 | MPa | Transverse, room temperature |
| Elongation (A) (min.) | ≥ 40 | % | 50 mm gauge, thickness ≤ 19.05 mm |
| Rockwell Hardness (max.) | 92 | HRB | Typical maximum (not mandatory) |
| Brinell Hardness (max.) | 201 | HBW | Typical maximum (not mandatory) |
| Impact Energy (KV) – not required | — | — | Austenitic steels not normally tested at room temperature |
ASTM A240 304L Stainless Steel Internationally Equivalent Standards – Fully Corresponding Grades
| Country / Region | Standard | Grade | Remarks |
|---|---|---|---|
| European Union | EN 10088-2 / EN 10088-3 | 1.4307 (X2CrNi18‑9) | Identical low‑carbon composition; widely accepted for pressure equipment |
| Japan | JIS G4304 / G4305 | SUS304L | Same carbon and chromium‑nickel limits |
| China | GB/T 3280 | 022Cr19Ni10 (old 00Cr19Ni10) | Harmonized with ASTM 304L |
| International | ISO 15510 | X2CrNi18‑9 | Equivalent to EN 1.4307, recognized globally |
ASTM A240 304L Stainless Steel Application Introduction
304L excels in applications where extensive welding is required without the risk of sensitization. Its excellent formability and corrosion resistance make it suitable for a broad spectrum of industries, from heavy chemical processing to delicate food‑contact surfaces. The following lists highlight typical end uses.
Product Applications: Storage tanks and pressure vessels, Piping systems and fluid transport ducts, Heat exchanger plates and shells, Commercial kitchen equipment and sinks, Architectural panels, fascias, and handrails, Brewery and dairy processing vats, Pharmaceutical clean‑room fixtures
Processed into products: Welded pipe fittings (elbows, tees, reducers), Flanges and gaskets for piping, Reactor vessel linings and internals, Agitator blades and mixer shafts, Heat exchanger tube sheets and baffles, Ductwork expansion joints, Brackets, supports, and fasteners for corrosive environments
Application industries: Chemical and petrochemical processing, Food and beverage manufacturing, Pharmaceutical and bioprocessing equipment, Architectural cladding and structural components, Automotive exhaust and trim (non‑structural), Pulp and paper industry, Water treatment and desalination
ASTM A240 304L Stainless Steel Similar / Alternative Materials
| Country / Region | Standard | Grade | Remarks |
|---|---|---|---|
| USA | ASTM A240 | 304 (UNS S30400) | Higher carbon (≤0.08%) limits as‑welded corrosion resistance; strength similar |
| USA | ASTM A240 | 304H (UNS S30409) | Carbon 0.04–0.10% for improved high‑temperature strength; lower formability |
| USA | ASTM A240 | 316L (UNS S31603) | Contains 2–3% Mo for better pitting resistance in chloride environments; comparable weldability |
| Europe | EN 10088-2 | 1.4301 (X5CrNi18‑10) | Standard 304 with higher carbon; less weldable for corrosion‑critical parts |
| Europe | EN 10088-2 | 1.4404 (X2CrNiMo17‑12‑2) | 316L equivalent, used when molybdenum‑enhanced resistance is needed |
Notes:
Welding considerations: 304L can be welded by all common processes (TIG, MIG, stick, SAW) without preheating. Post‑weld annealing is normally unnecessary due to low carbon content, although it may be required for heavy sections or to relieve stress. Corrosion: Resistant to a wide range of atmospheric environments and many organic and inorganic chemicals. Not recommended for chloride‑rich environments at elevated temperatures, where pitting or stress‑corrosion cracking may occur. Forming: Excellent cold forming and deep drawing characteristics; magnetic permeability may increase after severe cold work.
- Share
