Inconel Alloys
Inconel 625 (UNS N06625) — Composition, Properties & Supply
Inconel 625 (UNS N06625) is a Ni-Cr alloy strengthened mainly by molybdenum and niobium in solid solution. It reaches high strength without ageing heat treatment and offers a balanced combination of oxidation and corrosion resistance plus fatigue strength, making it one of the most widely used nickel alloys in offshore, chemical, nuclear and aerospace service.
What is the chemical composition of Inconel 625?
| Element | Symbol | Content (wt%) |
|---|---|---|
| Ni | Ni | ≥ 58.0 |
| Cr | Cr | 20.0–23.0 |
| Mo | Mo | 8.0–10.0 |
| Nb+Ta | Nb+Ta | 3.15–4.15 |
| Fe | Fe | ≤ 5.0 |
| Co | Co | ≤ 1.00 |
| Al | Al | ≤ 0.40 |
| Ti | Ti | ≤ 0.40 |
| C | C | ≤ 0.10 |
| Mn | Mn | ≤ 0.50 |
| Si | Si | ≤ 0.50 |
| P | P | ≤ 0.015 |
| S | S | ≤ 0.015 |
Values are typical specification limits. Actual heat analysis is reported on the EN 10204 3.1 mill test certificate supplied with each shipment.
What are the mechanical properties of Inconel 625?
| Property | Value | Note |
|---|---|---|
| Tensile strength | ≥ 830 MPa | Room temperature |
| Yield strength (0.2% offset) | ≥ 414 MPa | Room temperature |
| Elongation | ≥ 30 % | Gauge length 50 mm / 4D |
| Hardness | ≤ 200 HB | Brinell / Rockwell |
What are the physical properties of Inconel 625?
| Property | Value |
|---|---|
| Density | 8.44 g/cm³ |
| Melting range | 1290–1350 °C |
| Thermal conductivity | 9.8 W/m·K |
| Elastic modulus | 205 GPa |
| Maximum service temperature | 980 °C |
What are the key characteristics of Inconel 625?
- Reaches ~830 MPa tensile in the annealed condition without ageing
- Resists pitting, crevice corrosion and chloride stress-corrosion cracking
- PREN typically above 45; strong in seawater and sour gas
- Complies with NACE MR0175 / ISO 15156 for sour oil and gas
- Excellent weldability with matched ERNiCrMo-3 filler
Where is Inconel 625 used?
- Desalination and marine piping, pump shafts
- Flue-gas desulphurisation (FGD) systems
- Chemical reactors, heat exchangers and pickling equipment
- Nuclear and gas turbine piping systems
- Aero-engine exhaust systems and thrust reversers
- Sour oil and gas downhole tools and valves
Which standards and specifications cover Inconel 625?
What product forms are available?
Frequently asked questions
How do I choose between Inconel 625 and Inconel 718?
They are strengthened differently. 625 relies on Mo and Nb in solid solution, keeps its corrosion resistance as welded without post-weld heat treatment, and suits corrosion service and welded fabrications such as piping, vessels and seawater systems. 718 is precipitation hardened by γ″/γ′ and reaches roughly 1400 MPa after ageing, suiting highly stressed parts such as turbine discs and fasteners. Pick 625 when corrosion dominates and 718 when strength dominates.
Does Inconel 625 need post-weld heat treatment?
Normally no. As a solid-solution alloy it has no age-hardening requirement after welding. For thick or highly restrained fabrications, a stress relief at 870–980 °C may be used, avoiding the 650–870 °C sensitising range where carbides precipitate.
What is the typical PREN of Inconel 625?
Using PREN = %Cr + 3.3×%Mo + 16×%N with typical Cr 21.5% and Mo 9%, the value is about 51. With niobium contribution and measured data, engineering practice places 625 PREN in the 45–52 range — well above 316L (about 26) and 904L (about 36).
Need Inconel 625 bar, tube, plate or forgings?
Send the grade, dimensions, standard and quantity. We answer within 10 minutes on working days and quote within 24 hours, with EN 10204 3.1 certification.
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