Tube stainless steel Sanicro® 625

aeronautical

Sanicro® 625 is an extremely versatile nickel-chromium-molybdenum-niobium alloy suitable for severely corrosive environments requiring high strength. Service temperatures range from cryogenic to 593°C (1100°F).

Grade characteristics

• Excellent
  • Corrosion resistance in widely varying acidic and chloride-containing environments
  • Resistance to general corrosion, pitting and crevice corrosion
  • Resistance to corrosion in hydrogen sulfide environments
• Extremely good
  • Resistance to chloride-induced stress corrosion cracking
• Very high
  • Strength within the recommended service temperatures
• Very good
  • Welding properties

Material designations

• ASTM: UNS N06625 Grade 1
• UNS: N06625
• EN Number: 2.4856

Product standards

• ASTM B-446 (Grade 1) / ASME SB-446 (Grade 1)
• ANSI/NACE MR0175 / ISO 15156-3
• ANSI/NACE MR0103 / ISO 17945-1
• ISO14067:2018 (CO2e) — chemical composition and mechanical properties only
• ASTM B-564 / ASME SB-564

Approvals

• Pressure Equipment Directive / PED (2014/68/EU)
• Pre-approval for PMA, D≤254 mm
• Approved by the American Society of Mechanical Engineers (ASME) for use in accordance with ASME Boiler and Pressure Vessel Code, Section I, Section III Div.1 classes 1 and 3, Section VIII div.1

Climate change impact

• Carbon footprint / CO2e data (kg/ton) and Life Cycle Assessment report available for products in the range D 75-230 mm (D3.00”–9.05”)

Material Test Certificate

• According to EN 10204/3.1

Chemical composition (nominal) %

• C: <0.025
• Si: <0.50
• Mn: <0.50
• P: <0.015
• S: <0.015
• Cr: 21
• Ni: 62
• Mo: 8.5
• Fe: <5
• Nb: <3.5
• Co: <1.0
• Ti: 0.2
• Al: <0.40

Applications

• Environmental projects
  • Waste-to-Energy production
  • Pollution control equipment
  • Refuse-derived fuel plants
• Renewable energy
  • Solar power plants
  • Geothermal power
  • Bio-fuel production
• Oil & Gas / Refinery
  • Well construction and service
  • Gas lift equipment
  • Wellheads and Christmas trees
• Chemical processing
  • Phosphoric acid production
  • Pickling operations
• Marine applications
  • Drivetrain components
  • Offshore piping systems
  • Seawater coolant in industries

Corrosion resistance

• General corrosion
  • Excellent resistance to reducing, oxidizing and mixed corrosive environments; particularly good resistance to marine corrosion / seawater
• Intergranular corrosion
  • Stabilized against intergranular attack by niobium and extra low carbon; tested acc. to ASTM G-28 Method A (Streicher test), criteria: Max. 3 mm/year
• Stress Corrosion Cracking
  • High nickel content (62%) gives excellent resistance to chloride- and alkali-induced SCC; acceptable for oil & gas use per NACE MR 0175 / ISO 15156-3 with no environmental limits for partial pressures of H2S or elemental sulfur
• Pitting and crevice corrosion
  • Extraordinary resistance in seawater across a variety of temperatures; PRE ≥48

Forms of supply

• Diameters and finished condition
  • Stocked in imperial dimensions
  • Diameter range: 76.2 mm–228.6 mm (3”–9”)
  • Delivery condition: Soft annealed, peel-turned and ground to final finish
• Lengths
  • Delivered in random lengths of 3–6.9 m, depending on diameter
• Straightness (metric)
  • Height of arch: 2 mm/m
• Tolerances (metric)
  • Diameter tolerances: -0 / +0.79 mm
  • Surface finish: Ra, max. 3 µm

Heat treatment

• Stock program bars delivered soft annealed and quenched. Annealing at min. 910°C (1670°F) followed by quenching in water.

Mechanical properties (minimum values at room temperature)

• Tensile strength
  • Dimension D ≤ 101.9 mm: Proof strength Rp0.2 = 415 MPa / 60 ksi; Tensile strength Rm = 830 MPa / 120 ksi; Elongation A5 = 30%
  • Dimension D > 101.9 mm: Proof strength Rp0.2 = 345 MPa / 50 ksi; Tensile strength Rm = 760 MPa / 110 ksi; Elongation A5 = 30%
• Impact strength (-60°C)
  • Average Longitudinal: 68 J; Transversal (D > 60 mm): 47 J
  • Single: Longitudinal 61 J; Transversal 41 J
• Hardness
  • Max. 35 HRC in delivery condition

Physical properties

• Density at 20°C: 8.4 g/cm3 (0.31 lb/in3)

Thermal conductivity W/(m °C)

• 20°C: 9.8
• 100°C: 10.8
• 200°C: 12.5
• 300°C: 14.1
• 400°C: 15.7
• 500°C: 17.5
• 600°C: 19
• 700°C: 20
• 800°C: 22.8
• 900°C: 25.2

Specific heat capacity J/(kg °C)

• 20°C: 410
• 100°C: 427
• 200°C: 455
• 300°C: 475
• 400°C: 505
• 500°C: 525
• 600°C: 550
• 700°C: 575
• 800°C: 600
• 900°C: 625

Thermal expansion (mean values x10⁻⁶ per °C)

• 30–100°C: 12.5
• 30–200°C: 13
• 30–300°C: 13.5
• 30–400°C: 13.5
• 30–500°C: 14
• 30–600°C: 14
• 30–700°C: 15
• 30–800°C: 15.5
• 30–900°C: 16

Resistivity

• 20°C: 1.30 µΩm (51.2 µΩin.)
• 100°C: 1.32 µΩm (52.0 µΩin.)
• 200°C: 1.34 µΩm (52.8 µΩin.)
• 300°C: 1.35 µΩm (53.2 µΩin.)
• 400°C: 1.36 µΩm (53.5 µΩin.)
• 500°C: 1.37 µΩm (54.3 µΩin.)
• 600–900°C: approx. 1.38 µΩm (53.1–54.3 µΩin.)

Modulus of elasticity (x10³) — annealed condition

• 20°C: 208 GPa (30 ksi)
• 100°C: 203 GPa (29.5 ksi)
• 200°C: 198 GPa (28.5 ksi)
• 300°C: 193 GPa (28 ksi)
• 400°C: 187 GPa (27 ksi)
• 500°C: 181 GPa (26 ksi)
• 600°C: 174 GPa (24.5 ksi)
• 700°C: 166 GPa (23.5 ksi)
• 800°C: 156 GPa (21.5 ksi)

Welding

• Weldability is good. Suitable methods: MMA/SMAW and gas-shielded arc welding; TIG/GTAW is first choice.
• Recommended heat input <1.2 kJ/mm and interpass temperature <100°C (210°F); string bead technique advised.
• Recommended filler metals: TIG/GTAW or MIG/GMAW — ISO 18274 S Ni 6625 / AWS A5.14 ERNiCrMo-3 (e.g. Exaton Ni60). MMA/SMAW — ISO 14172 E Ni 6625 / AWS A5.11 ENiCrMo-3 (e.g. Exaton Ni60).

Machining

• Machining includes turning, milling, drilling and other subtractive operations; initial operations for solid bars are cutting and external turning to prepare blanks.
• Materials in ISO-S group are challenging to machine (difficult chip control, high cutting forces and tool wear); dedicated cutting tools and strategies are recommended. Consult tool supplier for start recommendations based on ISO material group, condition/heat treatment and actual hardness of the lot.

Caractéristiques / spécifications techniques

• Denomination commerciale: Sanicro® 625
• Manufacturer / brand: Alleima
• Material designations: UNS N06625, EN 2.4856
• Diameter range (stock): 76.2–228.6 mm (3”–9”)
• Lengths: random 3–6.9 m (depending on diameter)
• Delivery condition: Soft annealed, peel-turned, ground; annealing at ≥910°C quench in water
• Proof / tensile (min, room temp): D≤101.9 mm Rp0.2 415 MPa; Rm 830 MPa. D>101.9 mm Rp0.2 345 MPa; Rm 760 MPa
• Elongation (A5): 30%
• Impact (-60°C) average: Longitudinal 68 J, Transverse 47 J
• Hardness (delivery): max 35 HRC
• Density: 8.4 g/cm3
• Chemical composition: Ni ~62%, Cr ~21%, Mo ~8.5%, Nb <3.5%, others as listed
• PRE >48 (excellent pitting/crevice resistance)
• Standards & approvals: ASTM/ASME B-446/B-564, NACE MR0175 / ISO 15156-3, PED
• Datasheet updated: 2025-06-20 (supersedes previous editions)