904L — high-alloy austenitic stainless with 4-5% Mo. PRE=34. Resistant to H2SO4, phosphoric acid and chloride pitting. For chemical plant, acid pickling and desalination.
Standards
| Standard Body |
Designation |
Country |
| EN |
1.4539 / N08904 |
EU |
| UNS |
N08904 |
USA |
| ASTM |
A240 / A276 N08904 |
USA |
| BS EN |
904S13 |
UK |
| JIS |
SUS890L |
Japan |
| GOST |
03H20N16AG6 (nearest) |
Russia |
| ISO |
X1NiCrMoCu25-20-5 |
International |
| Trade |
Cronifer 1925 (ThyssenKrupp) / Nicrofer 2520 (ThyssenKrupp) |
Global |
| JUS |
1.4539 equivalent |
Yugoslavia |
Composition (wt.%)
| Element |
Symbol |
Min % |
Max % |
Typical % |
| Carbon |
C |
— |
0.020 |
0.010 |
| Silicon |
Si |
— |
1.000 |
0.500 |
| Manganese |
Mn |
— |
2.000 |
1.000 |
| Chromium |
Cr |
19.000 |
23.000 |
20.500 |
| Nickel |
Ni |
23.000 |
28.000 |
25.500 |
| Molybdenum |
Mo |
4.000 |
5.000 |
4.500 |
| Copper |
Cu |
1.000 |
2.000 |
1.500 |
Physical
Melting Range
1300 – 1350
°C
Thermal Conductivity
12
W/mK
Thermal Expansion
15.5
×10⁻⁶/K
Machinability
| Rating |
38.0% (B1112=100%) |
| Turning HSS |
15.0 m/min |
| Turning Carbide |
78.0 m/min |
| Surface Finish |
Ra 0.4-1.6 um |
| Coolant |
High-pressure flood coolant mandatory |
Mechanical
| Condition |
Rm (MPa) | Re (MPa) | A (%) |
HB | HRC | KV (J) | E (GPa) |
| Solution Annealed (+AT) |
≥490 |
≥220 |
≥35 |
≤220 |
— |
— |
195 |
Heat Treatment
| Process |
Temperature |
Medium |
Duration |
Hardness After |
| Solution Annealing |
1100 – 1150°C |
Water quench |
Sufficient |
<=HB 220 |
Applications
Chemical: H2SO4 service at all concentrations, H3PO4, organic acid processing equipment.
Pickling: Acid pickling tanks for steel strip, wire and tube pickling lines.
Desalination: Seawater desalination evaporator shells and heat exchanger bundles.
Pulp & Paper: Bleach plant wash press frames and filtrate systems.
Notes
904L vs 2205: PRE similar (~34 vs 35). 904L: better in H2SO4 (Cu+Ni effect) and reducing media. 2205: better strength (Rp0.2 450 vs 220 MPa), better pitting in seawater. Choose 904L for acid reducing service; 2205 for chloride oxidising service.
Sigma Phase: 904L is susceptible to sigma phase at 600-900 C — never use in this temperature range.