Alloy 20 vs 904L
These two grades are listed as equivalents of each other: their chemistry windows overlap and they serve the same applications. They are not always identical — check the differences below before substituting, especially in certified designs.
Alloy 20
Stainless Steel
Alloy 20 is a niobium-stabilized nickel-iron-chromium alloy with molybdenum and copper, developed specifically for hot sulfuric acid. It bridges stainless steels and nickel alloys: far better in reducing acids than 316L, at well below the cost of the high-nickel grades.
Standards: DIN 2.4660 · AISI UNS N08020 (Alloy 20)
904L
Stainless Steel
904L 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.
Standards: DIN 1.4539 · AISI 904L (UNS N08904) · GB 015Cr21Ni26Mo5Cu2
Chemical composition compared (%)
| Element | Alloy 20 | 904L |
|---|---|---|
| C | ≤0.07 | ≤0.020 |
| Si | ≤1.00 | ≤1.00 |
| Mn | ≤2.00 | ≤2.00 |
| P | ≤0.045 | ≤0.045 |
| S | ≤0.035 | ≤0.035 |
| Cr | 19.00–21.00 | 19.00–23.00 |
| Ni | 32.00–38.00 | 23.00–28.00 |
| Mo | 2.00–3.00 | 4.00–5.00 |
| Cu | 3.00–4.00 | 1.00–2.00 |
| Nb | 8×C–1.00 | — |
| N | — | ≤0.10 |
Properties compared
| Property | Alloy 20 | 904L |
|---|---|---|
| Delivery condition | Stabilization annealed | Annealed |
| Tensile strength | ≥550 MPa | 490–690 MPa |
| Yield strength | ≥240 MPa | — |
| Density | 8.08 g/cm³ | 7.90 g/cm³ |
| Hardness | — | ≤217 HB (annealed) |
| PREN | — | ~35 |
Sourcing either grade?
Nasteel stocks both families from Shenzhen with EN 10204 3.1 mill certificates by heat number.
Ask for a quotationSee full data sheets: Alloy 20 · 904L. Substitution decisions for certified parts stay with the design authority.