Bar and Rod
Plate and Sheet
Strip
Pipe and Tube
Wire
Welding
Powder Material
Cast Products
Forged Products
Fittings
Fastening
Round Bar:
φ2–500 mm, 1–6 m length
Flat/Square Bar:
4–100 mm thickness/width
Hex Bar:
A/F 3–100 mm
Hollow Bar:
OD 20–300 mm
Sheet:
0.3–6 mm thickness
Medium Plate:
6–25 mm thickness
Heavy Plate:
25–100 mm thickness
Standard Strip:
0.05–3 mm thick,
10–600 mm wide
Precision strip:
0.01–0.5 mm thick,
tight tolerance ±0.005 mm
Foil:
0.005–0.1 mm thick
Seamless Tube:
OD 6–450 mm,
WT 1–50 mm,
1–12 m length
Welded Tube:
OD 10–600 mm,
WT 1–20 mm
Capillary Tube:
OD 1–10 mm,
WT 0.1–2 mm
Wire Form:
Cold Drawn Wire,
Bright Wire,
Spring Wire,
Fine Wire,
Ultra-fine Wire
General Diameter:
φ0.1–10 mm
Coil Weight:
50–500 kg,
customizable tolerance
Solid Wire:
φ0.8–4.0 mm
Flux-cored Wire:
φ1.2–4.0 mm
Welding Rod:
φ2.0–5.0 mm
Powder Form:
AM 3D Printing Powder,
Spherical Powder,
Gas-atomized Powder,
Water-atomized Powder
Particle Size:
10–150 μm
Sphericity:
≥90% for AM grade
Cast Ingot:
φ200–800 mm
Precision Casting:
min wall 0.5 mm
Cast Pipe:
OD 100–600 mm,
WT 10–50 mm
Forged Bar:
Φ35–500 mm
Forged Ring:
OD 200–2000 mm
Forging Weight:
1–5000 kg
Fittings Form:
Elbow, Tee, Reducer, Flange, Cap, Outlet, Lap Joint
Size range:
1/2''–24'' (DN15–DN600)
Wall thickness:
Sch10–Sch160, STD, XS, XXS
Pressure Class:
150–2500 LB
Fastening Form:
Bolt, Nut, Screw, Stud, Washer, Pin, Rivet
Metric: M3–M64
Imperial: #4–2.5''
Length: 6–500 mm
904L is a high-alloy, low-carbon austenitic stainless steel with added molybdenum and copper. This datasheet presents the material within the American standard system.
With approximately 25% nickel, 20% chromium, 4.3% molybdenum and 1.5% copper, 904L offers corrosion resistance well above standard 18-8 grades, with a pitting-resistance equivalent number (PREN) around 34-36. The high nickel and molybdenum give strong resistance to chloride stress-corrosion cracking and to pitting, while the deliberate copper addition makes it especially resistant to sulphuric and phosphoric acids. The very low carbon (<=0.020%) ensures good resistance to intergranular corrosion after welding.
Typical applications include sulphuric-acid processing equipment, phosphoric-acid plant, flue-gas desulphurization, seawater and brackish-water systems, pulp-and-paper bleaching equipment, and components for the chemical, pharmaceutical and food industries.
Values for the solution-annealed condition.
| Property | Value | Unit |
|---|---|---|
| Density | 8.0 | g/cm³ |
| Melting range | 1300-1390 | °C |
| Young's modulus (20 °C) | 195 | GPa |
| Thermal conductivity (20 °C) | 12 | W/m·K |
| Coefficient of thermal expansion (20-100 °C) | 15.3 | µm/m·°C |
| Specific heat (20 °C) | 450 | J/kg·K |
| Electrical resistivity (20 °C) | ~0.95 | µΩ·m |
| Magnetic response | Non-magnetic (austenitic) | — |
Composition per ASTM A240.
| Element | Symbol | Min % | Max % | Role in Alloy |
|---|---|---|---|---|
| Iron | Fe | Balance | — | Base element |
| Nickel | Ni | 23.0 | 28.0 | Austenite stability; SCC resistance |
| Chromium | Cr | 19.0 | 23.0 | Passivity; corrosion resistance |
| Molybdenum | Mo | 4.0 | 5.0 | Pitting + crevice resistance |
| Copper | Cu | 1.0 | 2.0 | Sulphuric/phosphoric-acid resistance |
| Manganese | Mn | — | 2.0 | Deoxidiser |
| Silicon | Si | — | 1.0 | Deoxidiser |
| Carbon | C | — | 0.020 | Very low (intergranular resistance) |
| Phosphorus | P | — | 0.045 | Residual impurity |
| Sulphur | S | — | 0.035 | Residual impurity |
Nominal: 25Ni-20Cr-4.3Mo-1.5Cu. PREN ~ 34-36.
Solution-annealed condition, per ASTM A240 for UNS N08904.
| Property | Value | Unit |
|---|---|---|
| Tensile strength | >=490 | MPa |
| 0.2% yield strength | >=220 | MPa |
| Elongation at break | >=35 | % |
| Brinell hardness | <=90 | HRB |
Confirm against the mill test report.
| Environment | Performance | Notes |
|---|---|---|
| Sulphuric acid | Excellent | Cu addition is key |
| Phosphoric acid | Excellent | Including impure (wet-process) acid |
| Chloride pitting | Good | PREN ~34-36 |
| Crevice corrosion | Good | Better than 316L |
| Chloride SCC | Excellent | High Ni content |
| Acetic / formic acids | Excellent | Organic acids |
Resistance is intermediate between standard 316/317 grades and the 6Mo super-austenitics.
A solid-solution alloy; it is not hardenable by heat treatment.
Solution Anneal approximately 1090-1175 °C, followed by rapid cooling (water quench) to dissolve secondary phases and retain optimum corrosion resistance.
Readily weldable by GTAW, GMAW and SMAW. A matching or over-alloyed nickel-base filler is used to maintain corrosion resistance in the weld.
| Process | Applicability | Filler / Consumable |
|---|---|---|
| GTAW / TIG | Excellent | Matching 904L or Ni-base (e.g. ERNiCrMo-3) |
| GMAW / MIG | Good | Matching 904L or Ni-base |
| SMAW / stick | Good | Matching or Ni-base electrode |
No preheat required; control interpass temperature; post-weld heat treatment not normally required because of the low carbon.
Machining Guidelines
| Parameter | Recommendation |
|---|---|
| Machinability | Moderate; work-hardens; sharp tooling, slow-to-moderate speeds, positive feeds |
| Work hardening | Higher than carbon steel; avoid dwelling |
| Coolant | Ample flood coolant |
Forming Processes
| Process | Notes |
|---|---|
| Cold forming | Good ductility; work-hardens |
| Hot forming | ~1150-900 °C; solution anneal + quench afterward |
| Industry | Typical Components | Key Requirements |
|---|---|---|
| Chemical processing | Sulphuric/phosphoric-acid equipment | Cu-enhanced acid resistance |
| Flue-gas desulphurization | Scrubbers, ducting | Chloride + acid resistance |
| Pulp & paper | Bleaching equipment | Halide resistance |
| Marine / seawater | Heat exchangers, condensers | Pitting + SCC resistance |
| Oil & gas | Process equipment, tubing | Sour-service resistance |
| Product Form | Standard | Notes |
|---|---|---|
| Plate, sheet and strip | ASTM A240 / ASME SA-240 · UNS N08904 | — |
| Bar and shapes | ASTM A276 / A479 · UNS N08904 | — |
| Seamless / welded pipe | ASTM A312 / A790 · UNS N08904 | — |
| Seamless / welded tube | ASTM A249 / A269 · UNS N08904 | — |
| Forgings / fittings | ASTM A182 / B366 · UNS N08904 | — |
| Sour service | NACE MR0175 / ISO 15156 | Acid-gas applications |
High-alloy austenitic stainless steel. UNS N08904.
| UNS | Cr % | Mo % | Cu % | PREN | Best Used For |
|---|---|---|---|---|---|
| 904L | 19-23 | 4.0-5.0 | 1.0-2.0 | ~34 | Sulphuric/phosphoric acid; general |
| 316L | 16-18 | 2.0-3.0 | — | ~24 | General corrosion service |
| 317L | 18-20 | 3.0-4.0 | — | ~30 | Higher pitting than 316L |
| 254SMO | 19.5-20.5 | 6.0-6.5 | 0.5-1.0 | ~43 | 6Mo seawater service |
| 926 | 19-21 | 6.0-7.0 | 0.5-1.5 | ~43 | 6Mo seawater service |
021-33556635
13371897780
651280525@qq.com
No. 600, Si Chuang Road, Songjiang District, Shanghai
