Duplex 2507 is an outstanding representative of iron-based alloys (approximately 65% iron content). Its core secret lies in its carefully controlled dual-phase structure of austenite (γ) and ferrite (α). Incoloy 825, on the other hand, belongs to the nickel-iron-chromium alloy family (nickel content 38-46%, iron content ≥22%) and features a single-phase austenite structure. Its core competitiveness is built on its high nickel content.
HT PIPE is a 2507 stainless steel plate,incoloy 825 pipe supplier with 15+ export experience. Contact us for more information and quotes for free!
Super Duplex 2507 vs Incoloy 825: Material Comparison Table
| Property / Specification | Super Duplex 2507 (UNS S32750 / 1.4410) | Incoloy 825 (UNS N08825 / 2.4858) |
| Alloy Class | Ferritic-Austenitic Duplex Stainless Steel | Nickel-Iron-Chromium Alloy |
| Primary Composition | Fe (Bal), 25% Cr, 7% Ni, 4% Mo, 0.28% N | 38-46% Ni, Fe (Bal), 19.5-23.5% Cr, 2.5-3.5% Mo, 1.5-3% Cu |
| Microstructure | 50% Ferrite / 50% Austenite | Single-phase Austenite |
| Yield Strength (min) | ≥ 550 MPa | ≥ 240 MPa |
| Tensile Strength (min) | ≥ 800 MPa | ≥ 580 MPa |
| PREN (Pitting Resistance) | > 40 (Typically 42-45) | ~30-35 |
| Max Service Temperature | 300°C (572°F) due to embrittlement | up to 540°C (1000°F) |
ss2507 and alloy 825 Chloride Stress Corrosion Cracking (Cl-SCC)
2507: Its PREN value (pitting equivalent number) exceeds 40 (reaching 42-45). Its duplex structure physically blocks crack propagation paths. In seawater, high-temperature concentrated brine, and chloride-containing media, its Cl-SCC resistance surpasses that of 316L and 2205 duplex steels, and even outperforms some nickel-based alloys. When chloride ions are the primary threat and high stresses are present, 2507 is the undisputed first choice.
825: Its high nickel content provides excellent basic resistance, far exceeding that of ordinary austenitic stainless steels. However, in extreme environments with high temperatures (>80°C) and high chloride concentrations, its Cl-SCC resistance is significantly inferior to that of 2507.
alloy 2507 and alloy n08825 Pitting and Crevice Corrosion
2507: Its exceptionally high PREN value (42-45) is its formidable shield, derived from the exceptionally strong passivation film formed by high chromium, molybdenum, and nitrogen. Its resistance to localized corrosion in pure, high-chloride environments (such as seawater and saltwater) is exemplary.
825: With a PREN value of approximately 30-35, it relies on chromium and molybdenum for protection. Although its theoretical value in pure chloride environments is lower than 2507, its actual performance in complex mixed media such as sulfides and organic acids often exceeds PREN predictions, demonstrating excellent adaptability.
super duplex 2507 and incoloy 825 Reducing Acid Corrosion (Sulfuric Acid, Phosphoric Acid, etc.)
2507: While somewhat resistant to dilute sulfuric and phosphoric acids, it is by no means a formidable opponent. Its corrosion resistance rapidly diminishes at slightly higher concentrations or elevated temperatures, making it unsuitable for environments with strong reducing acids.
825: The synergistic effect of its high nickel content and the key copper element makes it the industry benchmark for reducing acid environments such as low- to medium-concentration sulfuric acid and full-concentration phosphoric acid. Its performance far exceeds that of all stainless steels and many nickel-based alloys.
uns s32750 and uns n08825 Sulfide Corrosion (H₂S/SSC)
2507: Meets the stringent NACE MR0175/ISO 15156 sour service conditions and is widely used in oil and gas environments containing H₂S/CO₂/Cl⁻. Careful attention must be paid to controlling the hardness after welding and processing to meet standard requirements.
825: Its high nickel content provides it with top-tier resistance to sulfide stress corrosion cracking (SSC), also meeting stringent NACE standards. In "hell-level" sour oil and gas environments with extremely high H₂S partial pressures and elemental sulfur (such as deep wells and high-sulfur oil and gas fields), its reliability and safety significantly outperform 2507, making it the preferred choice for core, high-risk pipelines.
s2507 and alloy 825 Mechanical Properties (Strength/Hardness/Wear Resistance)
2507: Yield strength (≥550 MPa) and tensile strength (≥800 MPa) are typically more than double those of 825 or 316L! Its exceptional hardness provides excellent wear and erosion corrosion resistance.
825: Its yield strength (≥240 MPa) and tensile strength (≥580 MPa) are comparable to those of 316L, but significantly lower than 2507. Its hardness is also lower, resulting in relatively average wear resistance. Its strength lies not in mechanical strength, but in its broad corrosion resistance.
s32750 steel pipe and incoloy n08825 High-temperature performance
2507: It has a well-defined operating window (≤300°C). Below 300°C, its strength and chloride corrosion resistance remain excellent. Above this temperature, strength decreases significantly, and there is a significant risk of σ phase precipitation (>~300°C), requiring strict control of high-temperature exposure time. Its oxidation resistance is limited (generally <600°C).
825: In the 500°C to 800°C range, its high-temperature strength and creep resistance far exceed those of stainless steel and 2507. It also boasts high microstructural stability and a low tendency to precipitate harmful phases. It also exhibits excellent oxidation resistance, allowing stable service up to approximately 540°C.
super duplex stainless steel 2507 and incoloy 825 Manufacturing Process (Welding/Processing)
2507: Welding requires extremely strict control of heat input and interpass temperature (<100°C), necessitating the use of specialized super-duplex steel consumables (such as ER2594). Sufficiently rapid cooling rates are required after welding to prevent the precipitation of brittle sigma phase and harmful nitrides. High non-destructive testing (RT/PT/UT) requirements are also present.
825: Relatively friendly (among nickel-based alloys). Its weldability is superior to that of high-alloy duplex steels. The use of matching nickel-based welding consumables (such as ERNiCrMo-3), controlled interpass temperatures (<150°C), and low heat input are recommended. Post-weld heat treatment is generally not required.
Procurement Support and Specifications
As an experienced international exporter, HT Pipeline supplies high-grade piping components in both materials to global standards:
Super Duplex 2507: Seamless & Welded Pipes (ASTM A789/A790), Plates (ASTM A240), and Pipe Fittings/Flanges (ASTM A182 F53).
Incoloy 825: Seamless Pipes (ASTM B423/ASME SB 423), Welded Pipes (ASTM B705), Plates (ASTM B424), and Flanges (ASTM B564 UNS N08825).
Request a Technical Consultation: Our engineering team can assist you in verifying material compatibility for your specific pressure, chemical media, and temperature limits.
Contact market@htpipe.com for product specifications, dimensional tolerances, and competitive pricing.
