Rod stainless steel SAF®2507+

SAF®2507+ is a high-alloy duplex (austenitic-ferritic) stainless steel designed for service in highly corrosive, chloride-containing environments. It is aligned to ISO 17781 and IOGP S-563 standards and supplied as solid round bar in solution annealed, quenched and peel-turned condition.

Grade characteristics

• Excellent: Resistance to stress corrosion cracking in chloride-bearing environments; Resistance to pitting and crevice corrosion
• Very high: Mechanical strength
• High: Resistance to general corrosion; Resistance to erosion corrosion and corrosion fatigue
• Good: Weldability

Material designations

• UNS: S32750
• EN Number: 1.4410
• EN Name: X2CrNiMoN25-7-4

Standards & product standards

• ISO 17781:2017 QL1 (D≤185 mm) and QL2 (D>185-200 mm)
• IOGP S-563:2018
• ASTM A-479 / ASME SA-479; ASTM A-276 / ASME SA-276
• EN 10088-3; EN 10088-5 (D≤160 mm)
• NORSOK M-630 2020 Rev.7, MDS D57 Rev.6 (D≤200 mm)
• NACE MR0175 / ISO 15156-3; NACE MR0103 / ISO 17945-1
• ISO 14067:2018 (CO2e)

Approvals

• Pressure Equipment Directive / PED (2014/68/EU)
• Pre-approval for PMA
• ISO17782:2018, NORSOK M650 Ed. 4
• DNV approved manufacturer

Chemical composition (nominal) %

• C: ≤0.030
• Si: ≤0.8
• Mn: ≤1.2
• P: ≤0.035
• S: ≤0.015
• Cr: 25
• Ni: 7
• Mo: 4
• N: 0.3
• Cu: ≤0.5

Applications

• Oil and gas industry
• Seawater cooling
• Salt evaporation industry
• Desalination plants
• Geothermal wells
• Refineries and petrochemical plants
• Mechanical components requiring high strength
• Pulp and paper industry

Corrosion resistance and related notes

• Highly resistant to organic acids (e.g. formic and acetic acid) even at high concentrations and temperatures compared with austenitic stainless steels
• Resistance to inorganic acids comparable to high-alloy austenitic stainless steels in certain ranges
• Excellent resistance to chloride-induced stress corrosion cracking
• Minimum PRE (Pitting Resistance Equivalent) = 41; PRE balanced in both ferrite and austenite phases
• Good resistance to erosion corrosion and corrosion fatigue due to high strength and improved corrosion resistance

Forms of supply

• Stocked solid round bar sizes: 20–250 mm (0.78”–7.87”)
• Delivered condition: solution annealed, quenched and peel-turned
• Lengths: random 3–7 m (9.84–22.96 ft) depending on diameter

Tolerances (diameter)

• 20–30 mm: 0 / +0.13
• >30–50 mm: 0 / +0.16
• >50–70 mm: 0 / +0.19
• >70–95 mm: 0 / +1.00
• >95–200 mm: 0 / +1.50

Straightness (height of arch, typical)

• Diameter 25–70 (75) mm: 1 mm/m (≈0.06” / 5 ft)
• Diameter >75 mm: 2 mm/m (≈0.12” / 5 ft)

Surface condition

• Diameter ≤200 mm (≤7.87”): Burnished, typical finish Ra ≈ 1 μm

Manufacturing & heat treatment

• All products manufactured at Alleima Tube AB integrated facility in Sandviken, Sweden (melting to testing)
• Solution annealing: slow heating up to 1000°C, anneal at 1050–1125°C followed by quenching
• Microstructure: austenitic-ferritic, ferrite content 35–55%, free from grain-boundary carbides and intermetallic phases

Mechanical properties (solution annealed and quenched)

• Proof strength Rp0.2 (min): 550 MPa
• Ultimate tensile strength Rm: 760–930 MPa
• Elongation: ≥25%
• For sizes below 50 mm, Rm min. 800 MPa (116 ksi) may apply
• Impact strength (Charpy-V longitudinal) at -50°C: ISO17781 QL1 D≤185 mm: 85 J average / 65 J single; QL2 D>185–200 mm: 65 J average / 50 J single; At 20°C: min 100 J average / 70 J single
• Hardness: Max 28 HRC

Physical & thermal properties (selected)

• Density: 7.8 g/cm³
• Specific heat capacity (approx.): 20°C: 490 J/(kg·°C)
• Thermal conductivity (W/(m·°C)) approx.: 20°C: 14; 400°C: 20
• Coefficient of thermal expansion (x10⁻⁶/°C) approx.: 30–100°C: 13.5; 30–400°C: 14.5
• Electrical resistivity (20°C): ~0.83 μΩ·m
• Modulus of elasticity (20°C): ~200 GPa

Welding & filler recommendations

• Good weldability; preferred methods TIG/GTAW, MMA/SMAW or gas-shielded arc welding
• Recommended heat input 0.2–1.5 kJ/mm and interpass temperature <150°C; preheating/post-weld heat treatment normally not necessary
• Recommended filler metals for GTAW/TIG: ISO 14343 S 25 9 4 N L / AWS A5.9 ER2594 (e.g. Exaton 25.10.4.L)
• Recommended MMA/SMAW: ISO 3581 E 25 9 4 N L R / AWS A5.4 E2594-16 and ISO 3581 E 25 9 4 N L B / AWS A5.4 E2594-15

Machining

• Suitable for turning, milling, drilling, cutting, boring, grinding, reaming and tapping; may require dedicated cutting tools and strategies due to ISO-M material group characteristics
• Start values should be selected based on material condition, hardness and consultation with cutting tool supplier

Caractéristiques / spécifications techniques

• Product name: SAF®2507+
• Denomination: SAF®2507+
• Material designations: UNS S32750; EN 1.4410; EN name X2CrNiMoN25-7-4
• Stock sizes: solid round bar 20–250 mm (0.78–7.87”)
• Lengths: random 3–7 m
• Chemical composition (nominal): see list above (C, Si, Mn, P, S, Cr, Ni, Mo, N, Cu)
• Proof strength Rp0.2 (min): 550 MPa; Rm: 760–930 MPa; Elongation ≥25%
• Density: 7.8 g/cm³; Hardness max: 28 HRC
• Standards: ISO 17781, IOGP S-563, ASTM A-479/A-276, EN 10088, NORSOK M-630, NACE MR0175/MR0103