Bar and Rod
Plate and Sheet
Strip
Pipe and Tube
Wire
Welding
Powder Material
Cast Products
Forged Products
Fittings
Fastening
Round Bar:
φ2–500 mm, 1–6 m length
Flat/Square Bar:
4–100 mm thickness/width
Hex Bar:
A/F 3–100 mm
Hollow Bar:
OD 20–300 mm
Sheet:
0.3–6 mm thickness
Medium Plate:
6–25 mm thickness
Heavy Plate:
25–100 mm thickness
Standard Strip:
0.05–3 mm thick,
10–600 mm wide
Precision strip:
0.01–0.5 mm thick,
tight tolerance ±0.005 mm
Foil:
0.005–0.1 mm thick
Seamless Tube:
OD 6–450 mm,
WT 1–50 mm,
1–12 m length
Welded Tube:
OD 10–600 mm,
WT 1–20 mm
Capillary Tube:
OD 1–10 mm,
WT 0.1–2 mm
Wire Form:
Cold Drawn Wire,
Bright Wire,
Spring Wire,
Fine Wire,
Ultra-fine Wire
General Diameter:
φ0.1–10 mm
Coil Weight:
50–500 kg,
customizable tolerance
Solid Wire:
φ0.8–4.0 mm
Flux-cored Wire:
φ1.2–4.0 mm
Welding Rod:
φ2.0–5.0 mm
Powder Form:
AM 3D Printing Powder,
Spherical Powder,
Gas-atomized Powder,
Water-atomized Powder
Particle Size:
10–150 μm
Sphericity:
≥90% for AM grade
Cast Ingot:
φ200–800 mm
Precision Casting:
min wall 0.5 mm
Cast Pipe:
OD 100–600 mm,
WT 10–50 mm
Forged Bar:
Φ35–500 mm
Forged Ring:
OD 200–2000 mm
Forging Weight:
1–5000 kg
Fittings Form:
Elbow, Tee, Reducer, Flange, Cap, Outlet, Lap Joint
Size range:
1/2''–24'' (DN15–DN600)
Wall thickness:
Sch10–Sch160, STD, XS, XXS
Pressure Class:
150–2500 LB
Fastening Form:
Bolt, Nut, Screw, Stud, Washer, Pin, Rivet
Metric: M3–M64
Imperial: #4–2.5''
Length: 6–500 mm
Alloy 625 is a nickel–chromium–molybdenum alloy with niobium additions, used for its high strength, excellent fabricability (including joining), and outstanding corrosion resistance. Service temperatures range from cryogenic to 982 °C (1800 °F). This datasheet presents the material within the American (ASTM / ASME / SAE-AMS / UNS) standard system.
Its strength derives from the stiffening effect of molybdenum and niobium on the nickel–chromium matrix, so precipitation-hardening treatments are not required. This same combination of elements gives superior resistance to a wide range of severe corrosive environments, as well as to high-temperature oxidation and carburisation. The high molybdenum content makes the alloy very resistant to pitting and crevice corrosion, while niobium stabilises it against sensitisation during welding; the high nickel content provides freedom from chloride-ion stress-corrosion cracking.
These properties make the alloy an excellent choice for sea-water and chemical-processing applications, aerospace ducting and engine-exhaust systems, and nuclear reactor-core and control-rod components. It offers freedom from local attack, high corrosion-fatigue strength, high tensile strength, and excellent weldability and brazeability across its full service range.
Typical values per Special Metals official datasheet, annealed condition.
| Property | Value | Unit |
|---|---|---|
| Density | 8.44 | g/cm³ |
| Melting range | 1290–1350 | °C |
| Elastic modulus (21 °C, annealed) | 207.5 | GPa |
| Shear modulus (21 °C, annealed) | 81.4 | GPa |
| Poisson's ratio (21 °C) | 0.278 | — |
| Specific heat capacity (21 °C) | 410 | J/kg·K |
| Electrical resistivity (21 °C) | 1.29 | µΩ·m |
| Thermal conductivity (21 °C) | 9.8 | W/m·K |
| Coefficient of thermal expansion (21–93 °C) | 12.8 | µm/m·°C |
| Magnetic permeability (200 Oe) | 1.0006 | Essentially non-magnetic |
| Curie temperature | <–196 | °C |
| Maximum service temperature | ~982 | °C |
Limiting composition per ASTM B443 / B446 (UNS N06625).
| Element | Symbol | Min % | Max % | Role in Alloy |
|---|---|---|---|---|
| Nickel (+ Cobalt) | Ni | 58.0 | balance | Austenitic FCC matrix; chloride SCC resistance |
| Chromium | Cr | 20.0 | 23.0 | Forms Cr₂O₃ scale; oxidation and corrosion resistance |
| Molybdenum | Mo | 8.0 | 10.0 | Solid-solution strengthening; pitting/crevice resistance |
| Niobium (+ Tantalum) | Nb | 3.15 | 4.15 | Matrix stiffening; stabilises against weld sensitisation |
| Iron | Fe | — | 5.0 | Residual |
| Carbon | C | — | 0.10 | Controlled |
| Manganese | Mn | — | 0.50 | Deoxidiser |
| Silicon | Si | — | 0.50 | Deoxidiser |
| Aluminium | Al | — | 0.40 | Residual; deoxidiser |
| Titanium | Ti | — | 0.40 | Residual; carbide former |
| Cobalt | Co | — | 1.0 | Residual (if determined) |
| Phosphorus | P | — | 0.015 | Residual impurity |
| Sulphur | S | — | 0.015 | Residual impurity |
Nominal room-temperature properties (composites for product sizes up to 4 in; not for specification purposes).
| Form / Condition | Tensile strength | Yield strength (0.2%) | Elongation | Hardness |
|---|---|---|---|---|
| Rod/Bar/Plate, As-Rolled | 827–1103 MPa | 414–758 MPa | 30–60 % | 175–240 HB |
| Rod/Bar/Plate, Annealed | 827–1034 MPa | 414–655 MPa | 30–60 % | 145–220 HB |
| Rod/Bar/Plate, Solution-Treated | 724–896 MPa | 290–414 MPa | 40–65 % | 116–194 HB |
| Sheet/Strip, Annealed | 827–1034 MPa | 414–621 MPa | 30–55 % | 145–240 HB |
| Tube/Pipe, Annealed | 827–965 MPa | 414–517 MPa | 30–55 % | — |
Low-temperature ductility and toughness are retained to –196 °C. Values are typical; confirm against the mill test certificate for each delivery.
| Environment | Performance | Notes |
|---|---|---|
| Sea water | Outstanding | Freedom from pitting and crevice attack; high corrosion-fatigue strength |
| Chloride stress-corrosion cracking | Outstanding | High Ni content gives immunity |
| Pitting and crevice corrosion | Outstanding | High Mo content |
| Oxidising acids | Excellent | Ni + Cr resist oxidising chemicals |
| Non-oxidising / reducing acids | Excellent | High Ni + Mo content |
| Mixed acids (e.g. HCl + HNO₃) | Excellent | Resists directly opposite corrosion types |
| High-temperature oxidation | Good | Protective oxide retained; scaling significant above ~982 °C |
| Carburisation | Good | Resists high-temperature carburisation |
| Weld sensitisation | Excellent | Nb stabilises against intergranular attack |
The alloy is matrix-stiffened, not precipitation-hardened; heat treatment is for annealing, stress relief, and solution treatment only.
Anneal Temperature: 927–1038 °C (1700–1900 °F), time commensurate with thickness Purpose: Softening and recrystallisation; recommended for service at 650 °C and below, and for fatigue/tensile-critical applications.
Solution Treatment Temperature: 1093–1204 °C (2000–2200 °F) Purpose: Optimum creep-rupture resistance for service above 650 °C.
Stress Relief Heating cold-drawn material at 595–760 °C reduces residual stress; virtually complete at 871 °C. Cooling rate has no significant effect on properties.
Readily joined by conventional welding processes. Matching filler metals are highly resistant to corrosion and oxidation and require no post-weld heat treatment to maintain strength and ductility from cryogenic to 982 °C. Niobium stabilisation prevents weld-zone sensitisation.
| Welding Process | Applicability | Filler / Consumable |
|---|---|---|
| GTAW / TIG | Excellent | AWS A5.14 ERNiCrMo-3 (Filler Metal 625) |
| GMAW / MIG | Excellent | AWS A5.14 ERNiCrMo-3 (Filler Metal 625) |
| SMAW / stick | Excellent | AWS A5.11 ENiCrMo-3 (Electrode 112) |
The filler metals are also used as "overmatching" products for joining 316/317 stainless, 6 % Mo super-austenitic stainless, and other Ni-Cr-Mo alloys.
Machining Guidelines
| Tooling | Surface Speed | Feed |
|---|---|---|
| High-speed steel | 4.0–10.7 m/min | 0.13–0.51 mm/rev |
| Coated carbide | 14–34 m/min | 0.13–0.51 mm/rev |
Forming Processes
| Process | Notes |
|---|---|
| Hot forming | Heat to (not above) 1175 °C; heavy forging 1175→1010 °C; light reductions down to 925 °C; 15–20 % minimum reductions |
| Cold forming | Standard processes; high work-hardening rate; tensile >2000 MPa achievable in fine wire after 75–90 % reduction |
| Annealing between operations | 927–1038 °C |
| Industry | Typical Components | Key Requirements |
|---|---|---|
| Marine | Mooring cables, propeller blades, exhaust ducts, undersea cable sheathing, submarine fittings | Sea-water pitting/crevice resistance; chloride SCC immunity |
| Aerospace | Ducting, engine-exhaust and thrust-reverser systems, honeycomb structures, bellows, turbine shroud rings | High strength + oxidation + thermal-fatigue resistance |
| Chemical processing | Reaction vessels, distillation columns, heat exchangers, transfer piping, valves, bubble caps | Broad-spectrum corrosion resistance |
| Nuclear | Reactor-core and control-rod components | Strength + pitting/SCC resistance in 260–316 °C water |
| Power generation | High-temperature tubing, bellows, seals | Allowable design strength at 649–760 °C |
| Product Form | ASTM Standard | ASME Code | AMS Standard |
|---|---|---|---|
| Rod and bar | ASTM B446 | ASME SB-446 | AMS 5666 |
| Forgings | ASTM B564 | ASME SB-564 | AMS 5666 |
| Wire | — | — | AMS 5837 |
| Plate, sheet and strip | ASTM B443 | ASME SB-443 | AMS 5599 / 5869 |
| Seamless pipe and tube | ASTM B444 / B829 | ASME SB-444 / SB-829 | AMS 5581 |
| Welded pipe / tube | ASTM B705 / B751 | ASME SB-705 / SB-751 | — |
| Fittings | ASTM B366 | ASME SB-366 | — |
| Welding consumables | AWS A5.14 ERNiCrMo-3 · AWS A5.11 ENiCrMo-3 | — | — |
ASME Boiler and Pressure Vessel Code approved (Section VIII Div. 1: Grade 1 to 649 °C, Grade 2 to 871 °C); listed in NACE MR0175.
| Alloy | Ni % | Cr % | Mo % | UTS (annealed) | Max Temp. | Best Used For |
|---|---|---|---|---|---|---|
| Alloy 625 | ≥58 | 20–23 | 8–10 | 827–1034 MPa | ~982 °C | Sea-water; chemical processing; universal corrosion |
| Alloy 600 | ≥72 | 14–17 | — | ~655 MPa | ~1095 °C | General high-temp; carburisation/nitriding |
| Alloy 601 | 58–63 | 21–25 | — | ~550 MPa | ~1250 °C(ox) | Cyclic oxidation; radiant tubes |
| Alloy 617 | 44.5 | 20–24 | 8–10 | ~734 MPa | ~1100 °C | Gas-turbine hot section; creep strength |
| Alloy 718 | 50–55 | 17–21 | 2.8–3.3 | ~1240 MPa(aged) | ~650 °C | High-strength age-hardenable structures |
| Alloy 825 | 38–46 | 19.5–23.5 | 2.5–3.5 | ~690 MPa | ~540 °C | Acid resistance; Fe-Ni-Cr-Mo economy grade |
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