904L Stainless Steel – Durable, High-Quality Alloy
Alloy 904L (UNS N08904) is a premium, low-carbon, high-alloy austenitic stainless steel designed for exceptional corrosion resistance in highly aggressive environments. This grade is widely used in industries where standard stainless steels like AISI 316L or AISI 317L do not meet the required corrosion performance.
Why Choose Alloy 904L?
The superior performance of 904L stainless steel comes from its high nickel (23–28%) and molybdenum (4–5%) content, along with copper (1–2%). This unique chemistry offers:
- Outstanding resistance to sulphuric, phosphoric, and acetic acids
- High resistance to pitting and crevice corrosion in chloride-rich environments
- Excellent resistance to stress corrosion cracking
- Superior corrosion performance compared to conventional chrome-nickel stainless steels
Note: Alloy 904L has limited use in hydrochloric acid environments.
Key Features & Benefits
- Non-magnetic in all conditions
- Excellent formability and weldability for complex fabrication
- Maintains high toughness even at cryogenic temperatures
- Resistant to intergranular corrosion after welding due to low carbon content
- Operates safely at service temperatures up to 450°C
Available Product Forms
- Sheets & Plates
- Pipes & Tubes – Seamless, Welded, Coiled, and Straight
- Bars & Rods
- Fittings – Elbows, Tees, Reducers, Flanges
Typical Applications of Alloy 904L
- Seawater cooling equipment
- Chemical processing plants (sulphuric, phosphoric, and acetic acids)
- Gas washing and scrubbing systems
- Condenser and heat exchanger tubes
- Control and instrumentation tubing
- Oil and gas processing equipment
Industries Using Alloy 904L
- Chemical Processing
- Oil & Gas
- Pharmaceutical Manufacturing
- Desalination Plants
- Pulp & Paper Industry
Chemical Composition of Alloy 904L (UNS N08904)
| Element | Min (%) | Max (%) |
| C | – | 0.02 |
| Mn | – | 2.00 |
| Ni | 23.0 | 28.0 |
| Cr | 19.0 | 23.0 |
| S | – | 0.003 |
| Mo | 4.0 | 5.0 |
| N | – | 0.10 |
| Cu | 1.0 | 2.0 |
| P | – | 0.03 |
| Si | – | 0.70 |
Mechanical Properties (Annealed Condition)
| Property | Imperial | Metric |
| Tensile Strength (min) | 71 ksi | 490 MPa |
| Yield Strength 0.2% (min) | 32 ksi | 220 MPa |
| Elongation (min) | 35% | – |
Physical Properties (Room Temperature)
| Density | 7.95 g/cm³ |
| Specific Heat (0–100°C) | 450 J/kg·K |
| Thermal Conductivity | 11.5 W/m·K |
| Thermal Expansion | 15.8 μm/m·°C |
| Modulus of Elasticity | 190 GPa |
| Electrical Resistivity | 9.52 μΩ·cm |
Manufacturing Standards
- ASTM A213 – Seamless Ferritic & Austenitic Alloy Steel Tubes
- ASTM A269 – Seamless & Welded Austenitic Stainless Steel Tubing
- ASTM A312 – Seamless & Welded Austenitic Stainless Steel Pipes
- BS EN 10216-5 – Stainless Steel Tubes for Pressure Purposes
- Custom specifications on request
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