Alloy 254 SMO / F44 (UNS S31254)
Alloy 254 SMO is a high-alloy austenitic stainless steel with elevated molybdenum and nitrogen content. It offers outstanding resistance to pitting, crevice corrosion, and stress corrosion cracking, particularly in seawater and aggressive chloride environments.
The alloy maintains good mechanical strength and fabricability, making it suitable for desalination plants, heat exchangers, chemical processing equipment, and offshore installations.
Specifications
- UNS: 531254
- ASTM: A182 F44, A276
- EN/DIN: 1.4547
- Structure: High-Alloy Austenitic
- Condition Supplied: Solution Annealed
Data Tables
Chemical Composition:
| C | Mn | P | S | Si | Cr | Ni | Ti | Mo | N | Cu | Fe | Co | Nb (+Ta) | V | W | Al | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Min | 19.5 | 17.5 | 6 | 0.18 | 0.5 | ||||||||||||
| Max | 0.02 | 1 | 0.03 | 0.01 | 0.8 | 20.5 | 18.5 | 6.5 | 0.22 | 1 | Bal |
Mechanical Properties:
| Material Grade | ASTM Standard | Desgnation(EN /UNS) | Yield Strength (MPa) | Yield Strength (KSI) | Tensile Strength (MPa) | Tensile Strength (KSI) | Elongation (%) | Reduction of Area (%) | Hardness(HRC/HBWMax) | Condition | |
|---|---|---|---|---|---|---|---|---|---|---|---|
| Duplex F44 | ASTM A276 / A182 / A479 | EN 1.4547(S31254) | 305 | 44.23659 | 655 | 94.99989 | 35 | 50 | - | Solution Annealed |
Physical Properties:
| Material Grade | Density (g/cm³) | Melting Range (°C) | Modulus of Elasticity (GPa) | Thermal Conductivity (W/m·K) | Thermal Expansion (×10⁻⁶ /°C) | Electrical Resistivity (µΩ·m) | Magnetic Behavior |
|---|---|---|---|---|---|---|---|
| F6NM | 7.8 | 1450–1500 | 200 | 23 | 10.5 | 0.6 | Magnetic |
Key Features
- Exceptional resistance to pitting and crevice corrosion
- Excellent performance in seawater and chlorides
- High resistance to stress corrosion cracking
- Higher strength than conventional austenitic grades
- Excellent fabricability
Applications
- Desalination plants
- Seawater handling systems
- Heat exchangers
- Offshore piping systems
- Chemical processing equipment