Alloy 625 (UNS N06625)
Solid-solution nickel–chromium–molybdenum–niobium alloy with outstanding corrosion resistance and strength without age hardening.
- UNS
- N06625
- W.Nr / EN
- 2.4856
- Density
- 8.44 g/cm³
- Service range
- Cryogenic to ~980 °C (oxidation)
About Alloy 625
Alloy 625 derives its strength from the solid-solution stiffening of molybdenum and niobium in a nickel–chromium matrix, so high mechanical properties are achieved without precipitation heat treatment. It resists a remarkably wide range of corrosive environments — from seawater and chloride pitting to hot mineral acids — and stays tough from cryogenic temperatures to elevated service.
Because the strengthening is built into the matrix, welded joints retain properties close to the parent metal, making the grade a frequent choice where fabricated assemblies must survive aggressive media. DMK Alloys manufactures Alloy 625 blanks, bars and shaped components for heat-resistant and corrosion-critical service.
Alloy 625 chemical composition (weight %)
| Element | Limit / range |
|---|---|
| Ni | ≥ 58.0 |
| Cr | 20.0 – 23.0 |
| Mo | 8.0 – 10.0 |
| Nb (+Ta) | 3.15 – 4.15 |
| Fe | ≤ 5.0 |
| Al | ≤ 0.40 |
| Ti | ≤ 0.40 |
| Co | ≤ 1.0 |
| C | ≤ 0.10 |
| Mn | ≤ 0.50 |
| Si | ≤ 0.50 |
| P | ≤ 0.015 |
| S | ≤ 0.015 |
Composition limits per the commonly referenced standards listed below. Order-specific limits may differ — confirm against the governing specification.
Alloy 625 mechanical properties (typical)
| Condition / form | Tensile, MPa | 0.2% Yield, MPa | Elongation, % |
|---|---|---|---|
| Bar, annealed, room temp. | ≥ 827 | ≥ 414 | ≥ 30 |
| Plate / sheet, annealed, room temp. | ≥ 827 | ≥ 414 | ≥ 30 |
Values are typical or specification-minimum levels for guidance only — not a guarantee of properties. Certified values are established by testing against the ordered specification.
Alloy 625 specifications & international equivalents
| System | Designation | Covers |
|---|---|---|
| UNS | N06625 | All product forms |
| AMS | AMS 5666 | Bars, forgings, rings |
| AMS | AMS 5599 | Sheet, strip, plate (annealed) |
| AMS | AMS 5837 | Welding wire |
| ASTM | ASTM B446 | Rod, bar |
| ASTM | ASTM B443 | Plate, sheet, strip |
| ASTM | ASTM B444 | Pipe, tube |
| BS | BS 3076 NA21 | Bars (UK cross-reference) |
| W.Nr / EN | 2.4856 · NiCr22Mo9Nb | European cross-reference |
Cross-references are for guidance; the governing document is always the specification cited on your purchase order or drawing.
Alloy 625 physical properties
| Property | Typical value |
|---|---|
| Density | 8.44 g/cm³ |
| Melting range | 1290 – 1350 °C |
| Modulus of elasticity (family-typical) | ≈ 200 – 220 GPa |
| Indicative service range | Cryogenic to ~980 °C (oxidation) |
Forms we manufacture
- Bars and billets
- Forged blanks
- Rings
- Machined components to drawing
Dimensional ranges and delivery conditions are confirmed per enquiry.
Where Alloy 625 earns its keep
Typically specified for:
- Hot-gas ducting
- Bellows
- Combustor hardware
- Seawater components
- Chemical-process equipment
Also consider
Alloy 718
UNS N07718 · W.Nr 2.4668AMS 5662 / 5663 / 5664 · AMS 5596 / 5597
Precipitation-hardenable nickel–chromium superalloy — the workhorse grade for rotating and structural parts operating to ~700 °C.
Alloy X
UNS N06002 · W.Nr 2.4665AMS 5536 · AMS 5754
Solid-solution nickel–chromium–iron–molybdenum alloy with an exceptional record in combustor and furnace hardware.
Alloy C-276
UNS N10276 · W.Nr 2.4819ASTM B574 · ASTM B575
Nickel–molybdenum–chromium alloy with near-universal resistance to aggressive chemical environments.
Request Alloy 625 to your specification
State the governing standard, form, dimensions, quantity and testing requirements — the export team responds with a manufacturer's quotation.