SS 904L — Sheet, Plate, Coil, Pipe & Tube & Fittings
Also sold as Alloy 904L · UNS N08904 · W.Nr 1.4539 · 2RK65
SS 904L is a super-austenitic stainless steel with high nickel, molybdenum and copper, chosen for dilute sulphuric acid, phosphoric acid and chloride-bearing cooling water. We supply it as sheet, plate, coil, pipe & tube, fittings, flanges, fasteners, with EN 10204 3.1 certificates, from Mumbai to India, the Gulf, South-East Asia, South America, Europe, the UK and the USA.
- UNS N08904
- W.Nr 1.4539
- PREN ≈ 35
- ρ 7.95 g/cm³
Reviewed by the Kanak Steel & Engineering Co. technical team · Updated October 2026
SS 904L Products
SS 904L Names, Designations & Composition
SS 904L is one alloy sold under several names. Its UNS number is N08904, the European material number is W.Nr 1.4539 and the EN name is X1NiCrMoCu25-20-5. The chart on the right shows the specified range of each main alloying element; the balance is the base metal.
SS 904L Specifications by Product — Which Standard Applies?
The material standard changes with the product form. This is the table buyers ask for most.
| Product | Material standard | Dimensions |
|---|---|---|
| SS 904L sheet | ASTM A240 | ASTM A480 / B906 |
| SS 904L plate | ASTM A240 | ASTM A480 / B906 / A20 |
| SS 904L coil | ASTM A240 | ASTM A480 |
| SS 904L pipe & tube | ASTM A312 (N08904) | ASME B36.19 / B36.10 |
| SS 904L fittings | ASTM A403 WP904L · ASTM A182 F904L | ASME B16.9 · B16.11 |
| SS 904L flanges | ASTM A182 F904L | ASME B16.5 · B16.47 |
| SS 904L fasteners | May be machined from ASTM A479 bar (UNS N08904), where applicable; finished fastener requirements are to the purchase specification or project drawing | ASME B18.2.1 · B18.2.2 |
SS 904L Chemical Composition
Under technical review for TDS.
| Element | Current requirement |
|---|---|
| Nickel | As specified |
| Chromium | As specified |
| Molybdenum | As specified |
| Copper | As specified |
| Carbon | As specified |
| Manganese | As specified |
| Silicon | As specified |
| Nitrogen | As specified |
| Phosphorus | As specified |
| Sulphur | As specified |
| Iron | As specified |
Numerical specification requirements are published only after the applicable current standard edition has been verified. Governing specification to be verified: ASTM A240 for UNS N08904.
SS 904L Mechanical Properties
Under technical review for TDS.
| Property | Current requirement |
|---|---|
| Tensile strength | As specified |
| Yield strength 0.2% | As specified |
| Elongation | As specified |
| Hardness | As specified |
Numerical specification requirements are published only after the applicable current standard edition has been verified. Governing specification and condition to be verified: ASTM A240 for UNS N08904 — Annealed plate & sheet.
Density & Physical Properties
| Property | Value |
|---|---|
| Density | 7.95 g/cm³ |
| Melting range | 1300 – 1390 °C |
| Magnetic | Non-magnetic (annealed) |
| PREN (approx.) | ≈ 35 |
SS 904L Equivalent Grades
SS 904L Corrosion Resistance — What Each Element Does
Elevated nickel gives far better resistance to chloride cracking than 316L.
Molybdenum lifts pitting resistance well above ordinary austenitic grades (screening PREN on the grade page).
Copper is what makes 904L the stainless steel of choice for dilute sulphuric acid.
Very low carbon limits carbide precipitation, so welds keep their corrosion resistance.
Where Is SS 904L Used? Applications
SS 904L vs 316L, 2205 and 825
| Grade | PREN (approx.) | Pick it for |
|---|---|---|
| SS 316 / 316L | ≈ 24 | Chloride-bearing process fluids, marine air and pharmaceutical service |
| Inconel 825 | ≈ 31 | Sulphuric and phosphoric acid service, chloride stress-corrosion cracking and sour gas |
| Duplex 2205 | ≈ 35 | Strength with chloride resistance at a stainless-steel budget |
| SS 904L | ≈ 35 | Dilute sulphuric acid, phosphoric acid and chloride-bearing cooling water |
Welding SS 904L
| Matching filler | ER385 (AWS A5.9) |
|---|---|
| Also used | ERNiCrMo-3 for severe chloride service |
SS 904L for export
FOB / CIF · Nhava Sheva (JNPT), MumbaiTechnical documentation
A Kanak Steel technical data sheet for this product is being prepared. It is released as a PDF only after the current standard text, each value and its evidence, and a named technical reviewer have been confirmed — so no draft or placeholder sheet is offered for download.
Need technical data now? Send your enquiry with the standard and edition you are ordering to.
| Document | SS 904L — Master grade technical data sheet |
|---|---|
| Document ID | KS-TDS-N08904-M |
| Grade | SS 904L |
| UNS | N08904 |
| Product form | All product forms (master) |
| Standard | ASTM A240 (current edition A240/A240M-26) ASTM A312 (current edition A312/A312M-25) ASTM A269 (current edition A269/A269M-25) ASTM A403 (current edition A403/A403M-26a) ASTM A182 (current edition A182/A182M-26a) Each form has its own standard — flat A240, pipe A312, tube A269 (A213 where supported), fittings A403, flanges A182 |
| Status | Under technical review for TDS |
- Technical Data Sheet — Under technical review
SS 904L — questions buyers ask
What is SS 904L?
SS 904L is a super-austenitic stainless steel with high nickel, molybdenum and copper. It is chosen for dilute sulphuric acid, phosphoric acid and chloride-bearing cooling water.
Which standards cover SS 904L products?
Sheet: ASTM A240; Plate: ASTM A240; Coil: ASTM A240; Pipe & Tube: ASTM A312 (N08904); Fittings: ASTM A403 WP904L · ASTM A182 F904L; Flanges: ASTM A182 F904L; Fasteners: May be machined from ASTM A479 bar (UNS N08904), where applicable; finished fastener requirements are to the purchase specification or project drawing. Always name the standard and edition on your order.
What is the UNS number of SS 904L?
UNS N08904, with the European material number W.Nr 1.4539.
What is the density of SS 904L?
7.95 g/cm³ — use it to calculate weights: plate kg = L(m) × W(m) × t(mm) × 7.95.
SS 904L or Inconel 825?
SS 904L suits dilute sulphuric acid, phosphoric acid and chloride-bearing cooling water; Inconel 825 is the step up for sulphuric and phosphoric acid service, chloride stress-corrosion cracking and sour gas.
Sources: the ASTM / ASME specifications named on this page and producer datasheets · Last updated October 2026