Alloy 904L
Introduction :
Fully austenitic, 904L is less sensitive to sigma phases and precipitation ferrite than other straight and high molybdenum austenitic grades. 904L combines relatively high insides of nickel molybdenum, chromium, and copper to provide more overall corrosion resistance, especially in phosphoric and sulfuric conditions. As a result, this grade offers features such as:
- A maximum service temperature of 450 ̊ C (824 ̊ F).
- Resilience against stress corrosion cracking.
- High resistance to crevice corrosion and pitting.
- Easy to weld and high formability
- More protection against intergranular corrosion.
- Very good resistance to stress corrosion cracking.
Chemical Composition for Alloy 904L
| C | Cr | Cu | Mn | Mo | Ni | P | S | Si |
|---|---|---|---|---|---|---|---|---|
| Max | – | – | Max | – | – | Max | Max | Max |
| 0.02 | 19.0 – 23.0 | 1.0 – 2.0 | 2.0 | 4.0 – 5.0 | 23.0 – 28.0 | 0.045 | 0.035 | 1.0 |
Physical Properties for Alloy 904L
| Grade | Density (kg/m3) |
Elastic Modulus (GPa) |
Mean Co-eff of Thermal Expansion (µm/m/°C) | Thermal Conductivity (W/m.K) |
Specific Heat 0-100°C (J/kg.K) |
Elec Resistivity (nΩ.m) |
|||
|---|---|---|---|---|---|---|---|---|---|
| 0-100°C | 0-315°C | 0-538°C | At 20°C | At 500°C | |||||
| 904L | 7900 | 190 | 15 | – | – | 11.5 | – | 500 | 952 |
Mechanical Properties for Alloy 904L
| Grade | Tensile Strength (MPa) min | Yield Strength 0.2% Proof (MPa) min | Elongation (% in 50mm) min | Hardness | |
|---|---|---|---|---|---|
| Rockwell B (HR B) | Brinell (HB) | ||||
| 904L | 490 | 220 | 36 | 70-90 typical | 150 |