904L Stainless Steel (1.4539)

Q: What are the Mechanical Properties of 904L Stainless Steel?

904L provides a balance of corrosion resistance, strength and formability. Typical values: tensile strength 515-690 MPa; yield strength 215-390 MPa; elongation 35-45 percent; hardness 217-269 HB; modulus of elasticity 193 GPa (28 x 10^6 psi). Suitable for heavy duty equipment and corrosive service.

Q: What are the Physical Properties of 904L Stainless Steel?

Typical values: density 8.0 g/cm3; melting point 1320-1390 C (2400-2550 F); modulus of elasticity 193 GPa; thermal conductivity approx 12 W/m K; thermal expansion approx 15 x 10^-6 per K. These support reliable operation under thermal cycling and mechanical stress.

Q: Are there variants of 904L stainless steel?

Examples sometimes referenced include: 904L Super Austenitic (higher molybdenum for pitting resistance); 904L Maraging (strength focused); 904L Duplex (austenitic corrosion resistance with ferritic strength); 904L Hyper Duplex (maximum corrosion and stress tolerance); 904L Super Austenitic Duplex (hybrid performance). Selection depends on corrosion, strength and fabrication needs.

Q: What is the Chemical Composition of 904L Stainless Steel?

Typical composition in percent: Chromium 19.0-23.0; Nickel 23.0-28.0; Molybdenum 4.0-5.0; Copper 1.0-2.0; Carbon 0.020 max; Manganese 2.00 max; Silicon 1.00 max; Phosphorus 0.045 max; Sulfur 0.035 max; Nitrogen 0.10 max; Iron balance. High Ni, Mo and Cu support resistance to acids, chlorides and pitting.

Q: Where is 904L stainless steel used?

Common applications: chemical processing (tanks, heat exchangers, reactors); oil and gas (offshore components, pipelines, risers); marine and shipbuilding (saltwater exposed parts, hull fittings, pumps); food and pharmaceutical (non reactive hygienic systems); power generation (condensers, heat exchangers); pulp and paper (acidic bleaching and digestion equipment).

High-alloy stainless steel for extreme corrosion resistance in acidic and chloride-rich environments.

904L Stainless Steel

904L stainless steel (1.4539 / UNS N08904) is a super austenitic alloy developed for outstanding performance in the harshest chemical, marine, and industrial settings. Its high levels of nickel (23–28%), molybdenum (4–5%), and copper (1–2%) provide exceptional resistance to reducing acids like sulfuric and phosphoric acid, outperforming standard stainless steels in both oxidising and reducing conditions.

With a low carbon content (≤ 0.020%), 904L avoids sensitisation during welding, preserving corrosion resistance even in heat-affected zones. It offers long-term durability in environments where chloride-induced stress corrosion cracking, pitting, and crevice corrosion are concerns, particularly in saltwater, process chemicals, and aggressive industrial atmospheres.

Thanks to its versatility and strength, 904L is widely used in pressure vessels, chemical tanks, heat exchangers, and marine equipment, where safety, hygiene, and structural integrity are non-negotiable.

AVAILABLE FORMS

Intamet offers 904 in a wide range of forms, including the below:

Tubes & Pipes

Fitting & Flanges

Round Bars

Sheet & Plate

FAQs: 904L Stainless Steel

What are the Mechanical Properties of 904L Stainless Steel?

904L stainless steel provides a strong balance between corrosion resistance, strength, and formability, making it suitable for both fabrication and high-performance end use.

Typical Mechanical Properties:

Tensile Strength: 515–690 MPa – Reliable performance in structural and pressurised environments.

Yield Strength: 215–390 MPa – Withstands significant load before deformation.

Elongation: 35–45% – Ensures ductility for bending, shaping, or welding.

Hardness: 217–269 HB – Delivers surface durability without compromising machinability.

Modulus of Elasticity: 193 GPa (28 x 10⁶ psi) – Maintains rigidity under stress.

These characteristics make 904L stainless steel suitable for heavy-duty equipment and corrosive service applications where long-term reliability is essential.

What are the Physical Properties of 904L Stainless Steel?

904L’s physical characteristics allow it to operate effectively under thermal cycling and mechanical stress in highly corrosive environments.

Typical Physical Properties:

Density: 8.0 g/cm³ – Stable and strong for structural applications.

Melting Point: 1320–1390 °C (2400–2550 °F) – Supports use in thermal processing equipment.

Modulus of Elasticity: 193 GPa – Prevents deformation under mechanical load.

Thermal Conductivity: ~12 W/m·K – Adequate heat dissipation in processing equipment.

Thermal Expansion: ~15 × 10⁻⁶ /K – Dimensional stability under temperature changes.

These properties allow 904L to maintain mechanical performance across chemical, marine, and power generation systems.

Are there variants of 904L stainless steel?

While 904L is already a high-performance alloy, several enhanced or hybrid variants have been developed to target niche applications with even higher stress, corrosion, or strength demands.

Common 904L Variants:

904L Super Austenitic: Higher molybdenum content for enhanced pitting and crevice corrosion resistance.

904L Maraging: Strengthened for aerospace and nuclear environments requiring extreme toughness.

904L Duplex: Combines austenitic corrosion resistance with ferritic strength and fatigue resistance.

904L Hyper Duplex: Engineered for maximum corrosion and stress tolerance in the harshest industrial settings.

904L Super Austenitic-Duplex: Hybrid design offering both exceptional mechanical performance and chemical stability.

These variants provide design flexibility across sectors requiring precise metallurgical and structural characteristics.

What is the Chemical Composition of 904L Stainless Steel?

904L’s superior corrosion resistance comes from its carefully balanced high-alloy formulation. Each element contributes to performance in chemically aggressive or chloride-heavy conditions.

Typical Composition (%):

Chromium (Cr): 19.00–23.00
Supports oxidation resistance and passivation.

Nickel (Ni): 23.00–28.00
Enhances stress corrosion resistance and stabilises the austenitic structure.

Molybdenum (Mo): 4.00–5.00
Increases resistance to pitting and crevice corrosion.

Copper (Cu): 1.00–2.00
Strengthens resistance to reducing acids like H₂SO₄ and H₃PO₄.

Carbon (C): ≤ 0.020
Prevents carbide precipitation during welding.

Manganese (Mn): ≤ 2.00
Improves hot working properties.

Silicon (Si): ≤ 1.00
Assists in oxidation resistance.

Phosphorus (P): ≤ 0.045
Limited to avoid brittleness.

Sulfur (S): ≤ 0.035
Controlled to support machinability without corrosion impact.

Nitrogen (N): ≤ 0.10
Enhances pitting resistance in combination with Mo.

Iron (Fe): Balance
Forms the base of the alloy.

This unique blend makes 904L a go-to alloy for systems involving aggressive acids, chlorides, and continuous exposure to corrosive stress.

Where is 904L Stainless Steel Used?

904L is widely specified for equipment and components operating in corrosive, high-stress, or chemically aggressive environments.

Common Applications:

Chemical Processing: Storage tanks, heat exchangers, and reactors exposed to strong acids.

Oil & Gas: Offshore components, pipelines, and risers subject to brine and high-pressure exposure.

Marine & Shipbuilding: Saltwater-exposed parts, hull fittings, and pumps.

Food & Pharmaceutical: Non-reactive and hygienic processing systems.

Power Generation: Condensers and heat exchangers requiring corrosion and heat resistance.

Pulp & Paper: Components exposed to acidic bleaching and digestion processes.

Its combination of corrosion resistance, weldability, and mechanical strength makes 904L stainless steel a trusted material across safety-critical sectors.

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904L Stainless Steel (1.4539)