Stainless Steel
Stainless Steel 904L (UNS N08904) — Composition, Properties & Supply
904L (UNS N08904) is a high-nickel, high-molybdenum copper-bearing superaustenitic stainless with PREN around 36. It far outperforms 316L in dilute sulphuric and phosphoric acid and chloride media, with markedly better stress-corrosion-cracking resistance.
What is the chemical composition of Stainless Steel 904L?
| Element | Symbol | Content (wt%) |
|---|---|---|
| Fe | Fe | Balance |
| Ni | Ni | 23.0–28.0 |
| Cr | Cr | 19.0–23.0 |
| Mo | Mo | 4.00–5.00 |
| Cu | Cu | 1.00–2.00 |
| Mn | Mn | ≤ 2.00 |
| Si | Si | ≤ 1.00 |
| C | C | ≤ 0.020 |
Values are typical specification limits. Actual heat analysis is reported on the EN 10204 3.1 mill test certificate supplied with each shipment.
What are the mechanical properties of Stainless Steel 904L?
| Property | Value | Note |
|---|---|---|
| Tensile strength | ≥ 490 MPa | Room temperature |
| Yield strength (0.2% offset) | ≥ 220 MPa | Room temperature |
| Elongation | ≥ 35 % | Gauge length 50 mm / 4D |
| Hardness | ≤ 200 HB | Brinell / Rockwell |
What are the physical properties of Stainless Steel 904L?
| Property | Value |
|---|---|
| Density | 8.00 g/cm³ |
| Melting range | 1300–1390 °C |
| Thermal conductivity | 12.0 W/m·K |
| Elastic modulus | 195 GPa |
| Maximum service temperature | 400 °C |
What are the key characteristics of Stainless Steel 904L?
- PREN around 36 — roughly 1.4 times the pitting resistance of 316L
- Copper markedly improves dilute sulphuric acid resistance
- High nickel (23–28%) resists stress-corrosion cracking
- Weldable with no post-weld heat treatment required
Where is Stainless Steel 904L used?
- Sulphuric and phosphoric acid plant
- Fertiliser and phosphate chemical units
- Seawater cooling and desalination
- Pulp, paper and pickling equipment
- Pharmaceutical and fine-chemical vessels
Which standards and specifications cover Stainless Steel 904L?
What product forms are available?
Frequently asked questions
How does 904L compare economically with 316L?
904L costs roughly 3–5 times 316L per kilogram but typically lasts several times longer in dilute sulphuric acid, phosphoric acid and chloride service. Where downtime is expensive and the medium aggressive, 904L has the lower life-cycle cost; for mild media such as clean water, steam or food-grade duties, 316L is more economical.
Need Stainless Steel 904L bar, tube, plate or forgings?
Send the grade, dimensions, standard and quantity. We answer within 10 minutes on working days and quote within 24 hours, with EN 10204 3.1 certification.
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