904L
Data verified904L is a high-nickel, molybdenum- and copper-bearing super-austenitic stainless developed for sulfuric acid and hot chloride service. Copper gives it resistance to reducing acids that defeat 316L, while 4–5% molybdenum covers pitting.
Chemical composition
| Element | Content (%) |
|---|---|
| C | ≤0.020 |
| Si | ≤1.00 |
| Mn | ≤2.00 |
| P | ≤0.045 |
| S | ≤0.035 |
| Cr | 19.00–23.00 |
| Ni | 23.00–28.00 |
| Mo | 4.00–5.00 |
| Cu | 1.00–2.00 |
| N | ≤0.10 |
Weight percent, per the governing standard ranges. Actual values per heat are on the mill certificate.
Properties
| Delivery condition | Annealed |
| Hardness | ≤217 HB (annealed) |
| Tensile strength | 490–690 MPa |
| Density | 7.90 g/cm³ |
| PREN | ~35 |
Heat treatment
Solution anneal 1060–1140 °C, rapid cool (water). Avoid holding between 600 and 900 °C.
Equivalent grades
| Standard | Designation |
|---|---|
| din | 1.4539 |
| aisi | 904L (UNS N08904) |
| gb | 015Cr21Ni26Mo5Cu2 |
Compare side by side: 904L vs 317L
Equivalents overlap in chemistry and use but are not always identical — see our equivalents guide before substituting in certified designs.
Applications & Processing
Applications: Sulfuric acid plant, phosphoric acid equipment, seawater coolers, offshore piping, paper bleach equipment.
Processing: Welds with over-alloyed nickel-base or matching fillers; fully austenitic weld metal needs controlled technique; machining is demanding due to work hardening.
FAQ
- 904L or 316L for seawater?
- 904L resists pitting and crevice corrosion in warm seawater far better than 316L, but for continuous immersed seawater duty the 6% Mo super-austenitics or super duplex 2507 are usually stronger choices.
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Ask for a quotationVisit NasteelSource: ASTM A240 / EN 10088 published ranges · Last updated 2026-11-03. Data is indicative — verify critical values against the governing standard and mill certificate before use.