Introduction to UNS N08904 Material
We present UNS N08904 material, globally recognized as 904L stainless steel, a high-alloy austenitic stainless steel engineered for extreme corrosion resistance and long-term performance in aggressive industrial environments. This grade is distinguished by its exceptionally high nickel and molybdenum content, combined with added copper, making it one of the most reliable materials for applications exposed to strong acids, chlorides, and seawater conditions.
UNS N08904 is widely specified across chemical processing, oil & gas, marine, pharmaceutical, power generation, and desalination industries, where standard stainless steels fail to deliver sufficient durability.
UNS N08904 Stainless Steel – Standard Designations and Equivalents
The UNS N08904 material is internationally standardized and equivalent to multiple global specifications, ensuring seamless procurement and application worldwide.
Common Standards and Equivalents:
UNS: N08904
EN: 1.4539
ASTM: AISI 904L
DIN: X1NiCrMoCu25-20-5
AFNOR: Z2 NCDU 25-20
JIS: SUS 904L
These equivalents ensure compatibility in engineering design, fabrication, and global supply chains.
Chemical Composition of UNS N08904 Material
The superior corrosion resistance of UNS N08904 stainless steel is achieved through a carefully optimized alloy chemistry.
| Element | Carbon (C) | Chromium (Cr) | Nickel (Ni) | Molybdenum (Mo) | Copper (Cu) | Manganese (Mn) | Silicon (Si) | Phosphorus (P) | Sulfur (S) | Iron (Fe) |
|---|---|---|---|---|---|---|---|---|---|---|
| Content (%) | ≤ 0.020 | 19.0 – 23.0 | 23.0 – 28.0 | 4.0 – 5.0 | 1.0 – 2.0 | ≤ 2.0 | ≤ 1.0 | ≤ 0.045 | ≤ 0.035 | Balance |
The high nickel and molybdenum levels, combined with copper, provide exceptional resistance to sulfuric acid, phosphoric acid, and chloride-rich environments.
Mechanical Properties of UNS N08904 Stainless Steel
UNS N08904 delivers excellent mechanical strength while maintaining ductility and toughness across a wide temperature range.
| Property | Value |
|---|---|
| Tensile Strength | ≥ 490 MPa |
| Yield Strength (0.2%) | ≥ 220 MPa |
| Elongation | ≥ 35% |
| Hardness | ≤ 90 HRB |
| Impact Strength | Excellent at low temperatures |
These properties make 904L stainless steel ideal for pressure equipment, heat exchangers, and structural components.
Physical Properties of UNS N08904 Material
| Property | Value |
|---|---|
| Density | 8.0 g/cm³ |
| Melting Range | 1300 – 1390°C |
| Thermal Conductivity | 12 W/m·K |
| Electrical Resistivity | 0.78 µΩ·m |
| Coefficient of Expansion | 15.8 µm/m·°C |
The stable physical behavior ensures dimensional accuracy and reliability during fabrication and service.
Corrosion Resistance of UNS N08904 Stainless Steel
The defining advantage of UNS N08904 material is its exceptional corrosion resistance.
Key Resistance Capabilities
Outstanding resistance to sulfuric and phosphoric acids
Superior performance in chloride-bearing environments
High resistance to pitting and crevice corrosion
Excellent immunity to stress corrosion cracking
Reliable service in seawater and brine solutions
Compared to 316L stainless steel, UNS N08904 offers significantly enhanced corrosion protection, extending service life and reducing maintenance costs.
Fabrication and Weldability of UNS N08904 Material
UNS N08904 stainless steel exhibits excellent fabrication characteristics despite its high alloy content.
Forming
Suitable for cold and hot forming
Requires higher forming forces than 304 or 316
Maintains ductility after deformation
Machining
Machinability is moderate
Sharp tools and controlled speeds recommended
Adequate cooling improves tool life
Welding
Excellent weldability using matching filler metals
No post-weld heat treatment required
Low carbon content prevents carbide precipitation
These attributes make UNS N08904 ideal for complex fabricated equipment.
Available Forms of UNS N08904 Stainless Steel
We supply UNS N08904 material in a comprehensive range of industrial forms:
Seamless & Welded Pipes and Tubes
Plates, Sheets & Coils
Bars & Rods
Forged Components
Pipe Fittings
Flanges
Fasteners
Custom sizes and finishes are available to meet project-specific requirements.
Industrial Applications of UNS N08904 Material
The versatility and reliability of UNS N08904 stainless steel make it indispensable across critical industries.
Chemical & Petrochemical Industry
Heat exchangers
Acid reactors
Storage tanks
Piping systems
Oil & Gas Sector
Offshore platforms
Gas processing equipment
Desalination units
Marine & Offshore
Seawater piping
Condensers
Marine hardware
Power Generation
Flue gas desulfurization systems
Condensers
Cooling systems
Pharmaceutical & Food Processing
Hygienic piping
Process vessels
Heat transfer equipment
Advantages of Choosing UNS N08904 Stainless Steel
Extended service life in aggressive environments
Reduced downtime and maintenance
Excellent lifecycle cost efficiency
Global standard compliance
High reliability under extreme conditions
These advantages make UNS N08904 material a strategic investment for long-term industrial performance.
Comparison: UNS N08904 vs 316L Stainless Steel
| Property | UNS N08904 | 316L Stainless Steel |
|---|---|---|
| Nickel Content | Very High | Moderate |
| Molybdenum | High | Lower |
| Copper | Present | Absent |
| Acid Resistance | Excellent | Limited |
| Chloride Resistance | Superior | Moderate |
| Cost | Higher | Lower |
Conclusion
UNS N08904 material stands as a benchmark in high-performance stainless steel alloys, delivering unmatched corrosion resistance, mechanical stability, and fabrication versatility. Its proven performance across demanding industries confirms its position as a premium material choice for engineers and project developers seeking reliability, safety, and long-term value.
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