Physical properties
| Density | 8.0 | g/cm³ |
| Modulus E | 195 / 190 / 182 / 174 / 166 / 158 | GPa @ 20 / 100 / 200 / 300 / 400 / 500 °C |
| Thermal conductivity | 12 | W/(m·K) @ 20 °C |
| Thermal expansion | 15.8 / 16.1 / 16.5 / 16.9 / 17.3 | 10⁻⁶/K, mean 20-100 / 20-200 / 20-300 / 20-400 / 20-500 °C |
| Specific heat | 450 | J/(kg·K) @ 20 °C |
| Resistivity | 1.00 | Ω·mm²/m @ 20 °C |
Informative values: they vary with composition, condition and test method. Use the governing standard or measured mill data for pressure and heat-transfer calculations.
Values are taken from EN 1.4539 (the same alloy) and are informative.
Chemical composition
Nominal: mid-range where both limits are given, the cap where only a maximum is, balance takes the remainder. Exact specified ranges below.
| Element | Name | Content % | |
|---|---|---|---|
| Main elements5 elements | |||
| Fe | Iron | Bal. | |
| Ni | Nickel | 23 – 28% | |
| Cr | Chromium | 19 – 23% | |
| Mo | Molybdenum | 4 – 5% | |
| Cu | Copper | 1 – 2% | |
| Element | Name | Content % | |
|---|---|---|---|
| Minor & residual6 elements | |||
| N | Nitrogen | ≤ 0.1% | |
| C | Carbon | ≤ 0.02% | |
| Mn | Manganese | ≤ 2% | |
| Si | Silicon | ≤ 1% | |
| P | Phosphorus | ≤ 0.045% | |
| S | Sulphur | ≤ 0.035% | |
Mechanical minima by form
Guaranteed values differ by form, size and delivery condition; quotations confirm the specification, form, size and condition.
| Form | Condition | Rm MPa | Rp0.2 MPa | A ≥ % | Other requirements and notes |
|---|---|---|---|---|---|
| Bar and forgings | |||||
| Bar and shapes | Condition A; solution treated at not less than 1095 °C, water quenched or otherwise rapidly cooled | ≥ 490 (71 ksi) | ≥ 220 (32 ksi) | ≥ 35 | |
| Pressure-retaining forgings (1.4539, reference section ≤160 mm) | +AT: solution treated at 1060–1120 °C, water cooled | 520 – 720 | ≥ 220 | ≥ 35 | |
| Bars and shapes (boiler and pressure-vessel use) | Annealed | ≥ 490 (71 ksi) | ≥ 220 (32 ksi) | ≥ 35 | |
| Bars (EN 10088-3, ≤160 mm) | +AT (solution annealed) | 530 – 730 | ≥ 230 | ≥ 35 | Also specified: Hardness ≤ 230 HBW Rp1.0 ≥ 260 MPa; KV ≥ 100 J longitudinal; 160–250 mm: transverse A ≥ 30 %, KV ≥ 60 J. |
| Plate, sheet and strip | |||||
| Plate, sheet and strip | Solution annealed | ≥ 490 (71 ksi) | ≥ 220 (32 ksi) | ≥ 35 | Also specified: Hardness ≤ 90 HRB |
| Cold-rolled strip (EN 10088-2, ≤8 mm) | +AT (solution annealed) | 530 – 730 | ≥ 240 | ≥ 35 | Rp1.0 ≥ 270 MPa. |
| Hot-rolled plate (EN 10088-2, ≤75 mm) | +AT (solution annealed) | 520 – 720 | ≥ 220 | ≥ 35 | Rp1.0 ≥ 260 MPa; hot-rolled strip (≤13.5 mm): Rm 530–730 MPa. KV ≥ 100/60 J (long./transv., over 10 mm). |
| Tube and pipe | |||||
| Seamless pressure tubes (EN 10216-5, wall ≤60 mm) | +AT (solution annealed) | 520 – 720 | ≥ 230 | ≥ 35 | Rp1.0 ≥ 250 MPa; transverse A ≥ 30 %; KV ≥ 120/90 J (long./transv.). |
| Welded pressure tubes (EN 10217-7, wall ≤60 mm) | +AT (solution annealed) | 520 – 720 | ≥ 220 | ≥ 35 | As above |
| Fittings and flanges | |||||
| Factory-made fittings | Solution treated at 1085–1149 °C, rapidly cooled in water or otherwise; all welding must be completed before the final heat treatment | ≥ 490 (71 ksi) | ≥ 215 (31 ksi) | ≥ 28 | |
| Fittings (wrought austenitic stainless, butt-weld / socket) | Solution annealed 1985–2100 °F [1085–1149 °C], water quenched or otherwise rapidly cooled | ≥ 490 (71 ksi) | ≥ 215 (31 ksi) | ≥ 28 | Elongation: ≥28% longitudinal, ≥20% transverse. A single temperature is a minimum. All fittings are supplied heat-treated. |
| Several forms | |||||
| Plate, bar, welded pipe and seamless pipe (former B-series specifications) | Applies only under superseded editions | — | — | — | |
Where this grade is recommended
Matched in 2 service conditions; ranks and scores computed from the condition-scoring matrix.
| Service condition | Industry | Temperature | Rank | Score |
|---|---|---|---|---|
| Sulphuric acid | Chemical Processing | > 200 °C | 1 / 8 | 90 |
| API synthesis vessels | Pharma & Fine Chemicals | 150 – 250 °C | 3 / 6 | 86 |
Designations & equivalents
| W.Nr. (Germany) | 1.4539 |
| EN designation | X1NiCrMoCu25-20-5 |
| Trade name(s) | 904L / Uranus B6 / Cronifer 1925 |
| ASTM / AISI | A240 / A276 / A403 / A479 / A484 / B625 / B649 / B673 / B677 |
| JIS (Japan) | SUS890L |
Cross-references are common near-equivalents for search and shortlisting; substitution across standards requires clause-by-clause verification. All grades in one cross-reference table →
Applicable standards
13 specifications. Name the standard and its edition on the order.
Guaranteed values and required tests differ between specifications — see Mechanical minima by form for the figures per form.
Frequently asked questions
What is 904L Super-Austenitic · UNS N08904?
904L Super-Austenitic · UNS N08904 — Super-austenitic stainless. The dilute-sulphuric classic — chemical, pharma and FGD service
What is the maximum service temperature of N08904?
Typically about 400 °C; the practical limit depends on media, stress and design life — acceptance per the governing standard.
What is the tensile strength of N08904?
The specified minimum tensile strength is 490 MPa for the main product form. Minima for other forms and sizes are listed under "Mechanical minima by form" on this page.
Which standards cover N08904?
ASTM A240/A240M, ASTM A480/A480M, ASTM A276/A276M, ASTM A479/A479M, ASTM A484/A484M, ASTM A403/A403M, ASTM A312/A312M, EN 10088-2 (sheet, plate, strip), EN 10222-5 (forgings for pressure purposes), EN 10088-3 (bar, rod, wire, sections), EN 10216-5 (seamless pressure tubes), EN 10217-7 (welded pressure tubes), ASTM A182/A182M
Where is N08904 typically used?
Sulphuric acid (Chemical Processing); API synthesis vessels (Pharma & Fine Chemicals)
In which forms is N08904 available?
Tube, plate, strip, bar, forgings, wire and other forms — sizes and delivery condition confirmed per order, with EN 10204 3.1 / 3.2 certification.
Same series
Download PDF datasheet
This grade’s datasheet as an A4 PDF — for filing, printing or forwarding to colleagues.
Download PDF datasheetSupply & enquiry
Tube & pipeφ1 – 219 × 0.25 – 25 mm
Plate4.76 – 80 mm
Barφ8 – 300 mm
Wire & filler metalsφ0.01 – 8 mmFor this grade we can supply, against your service conditions:
- Tube, plate, strip, bar, forgings, wire and more — with size range and lead time
- Chemistry and mechanical test report (EN 10204 3.1 / 3.2)
- Like-for-like alternatives and selection advice
- Applicable standards and inspection scope
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