Surface Treatments
Certifications
- ISO 9001:2015
- NORSOK M-650
- NACE MR0175
- ISO 15156-3
- PED 2014/68/EC
- EN 10204 type 3.2
- AD 2000 W2/W7/W10
Duplex 2205 vs Super Duplex 2507, Standard Duplex vs Super Duplex
Duplex 2205 (UNS S31803 / S32205, EN 1.4462) is the most-specified standard duplex stainless steel grade. Super Duplex 2507 (UNS S32750, EN 1.4410) is one tier above Duplex 2205 in the duplex / super duplex stainless steel family. The two are not direct substitutes, Duplex 2205 sits at PREN ~35 (standard duplex), Super Duplex 2507 at PREN ~42 (super duplex). The Duplex 2205 vs Super Duplex 2507 question is typically an upgrade decision: when do service conditions exceed Duplex 2205 limits and require super duplex?
Composition Comparison, Duplex 2205 vs Super Duplex 2507
| Element | Duplex 2205 (S31803/S32205) | Super Duplex 2507 (S32750) |
|---|---|---|
| Carbon (C), max. | 0.030 | 0.030 |
| Chromium (Cr) | 21.0–23.0 | 24.0–26.0 |
| Nickel (Ni) | 4.5–6.5 | 6.0–8.0 |
| Molybdenum (Mo) | 2.5–3.5 | 3.0–5.0 |
| Nitrogen (N) | 0.08–0.20 | 0.24–0.32 |
| Copper (Cu) | none | max 0.5 (not specified) |
Composition jump from Duplex 2205 to Super Duplex 2507: +3% Cr, +1% Mo, +0.12% N. Both grades have no Cu addition (for Cu-bearing super duplex, see Ferralium 255).
PREN Comparison
Duplex 2205 PREN = 22 + 3.3 × 3 + 16 × 0.15 ≈ 34.3 minimum, ~35 typical. Super Duplex 2507 PREN = 25 + 3.3 × 4 + 16 × 0.27 ≈ 42.5 typical. The 7+ PREN unit gap reflects the substantially better chloride pitting resistance of Super Duplex 2507. Critical Pitting Temperature (ASTM G48 method A): Duplex 2205 ~25 °C; Super Duplex 2507 ~40 °C, a ~15 °C extension of the chloride pitting service envelope.
Mechanical Properties Comparison
| Property | Duplex 2205 | Super Duplex 2507 |
|---|---|---|
| Yield strength (Rp0.2), min | 450 MPa | 550 MPa |
| Tensile strength (Rm), min | 620 MPa | 795 MPa |
| Elongation (A5), min | 25% | 15% |
| Hardness (NACE MR0175), max | 32 HRC | 32 HRC |
| Charpy at −46 °C, min (NORSOK) | 45 J | 45 J |
| Density | 7.80 g/cm³ | 7.80 g/cm³ |
When to Upgrade From Duplex 2205 to Super Duplex 2507
- Seawater service above 30 °C (Duplex 2205 CPT marginal at warmer temperatures)
- Sour-gas H2S partial pressure exceeding NACE MR0175 limits for standard duplex
- High-chloride concentrated brines (evaporator service, geothermal)
- NORSOK M-650 MDS D54 specification calling for super duplex 2507 by name
- High-velocity erosion-corrosion service in chloride environments
Super Duplex 2507 vs Ferralium 255, Within Super Duplex
Among super-duplex grades, Super Duplex 2507 and Ferralium 255 are interchangeable for chloride-pitting-dominated service (seawater, NORSOK offshore). The differentiator: Ferralium 255's 2% Cu addition gives improved performance in reducing-acid environments (HCl, dilute H2SO4, brines), making it preferred for chemical processing service combining chloride and reducing acids. See Ferralium 255 vs Super Duplex 2507 comparison and Ferralium 255 vs Duplex 2205 upgrade guide.
ASTM Specifications
Both Duplex 2205 (UNS S31803, S32205) and Super Duplex 2507 (UNS S32750) are covered by the same ASTM specification family across product forms: ASTM A479 (bar), A789 (tube), A790 (pipe), A815 (fittings), A182 (forgings, F51/F60 for 2205, F55 for 2507), A240 (plate / sheet). EN equivalents: EN 10088-3 (1.4462 / 1.4410), EN 10222-5 (forgings), EN 10272 (pressure-rated bar).
Need Duplex 2205 or Super Duplex 2507? Email info@torqbolt.com or WhatsApp +91-22-66157017 with form, dimensions, quantity, ASTM/EN spec, MTC level (3.1 / 3.2). NACE MR0175 sour-service stamp on every heat. NORSOK M-650 QTR on request. Per-heat EN 10204 type 3.2 MTC included with every consignment.
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