Alloy 20 vs 254 SMO
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)
254 SMO
Stainless Steel
254 SMO is a 6% molybdenum super-austenitic stainless with nitrogen and copper, giving a PREN above 42. It was developed for seawater and hot chloride service where 316L pits and even 904L runs out of margin.
Standards: DIN 1.4547 · AISI UNS S31254 (254 SMO) · GB 015Cr20Ni18Mo6CuN
Chemical composition compared (%)
| Element | Alloy 20 | 254 SMO |
|---|---|---|
| C | ≤0.07 | ≤0.020 |
| Si | ≤1.00 | ≤0.80 |
| Mn | ≤2.00 | ≤1.00 |
| P | ≤0.045 | ≤0.030 |
| S | ≤0.035 | ≤0.010 |
| Cr | 19.00–21.00 | 19.50–20.50 |
| Ni | 32.00–38.00 | 17.50–18.50 |
| Mo | 2.00–3.00 | 6.00–6.50 |
| Cu | 3.00–4.00 | 0.50–1.00 |
| Nb | 8×C–1.00 | — |
| N | — | 0.18–0.22 |
Properties compared
| Property | Alloy 20 | 254 SMO |
|---|---|---|
| Delivery condition | Stabilization annealed | Solution annealed |
| Tensile strength | ≥550 MPa | ≥690 MPa |
| Yield strength | ≥240 MPa | ≥310 MPa |
| Density | 8.08 g/cm³ | 8.00 g/cm³ |
| Hardness | — | ≤220 HB (annealed) |
| PREN | — | ≥42 |
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 · 254 SMO. Substitution decisions for certified parts stay with the design authority.