Nickel Alloy Inconel 625
UNS N06625 · ASTM B443 · EN 2.4856, NiCr22Mo9Nb · GB GH3625
Inconel 625 (UNS N06625, GH3625, 2.4856, NiCr22Mo9Nb) is a solid-solution-strengthened Ni-Cr-Mo-Nb alloy that develops strength from molybdenum and niobium rather than from aging.
Values for the O condition
Inconel 625 tempers and conditions
Inconel 625 is supplied in 10 conditions, soft to hard. O is the default FabDigit quotes; the values on this page are for it.
- Grade 2 Solution Treated
- Solution Annealed
- HIP
- O
- As Welded
- Hot Finished
- Stress Relieved
- As Printed
- Aged
- Cold Drawn
Compare all 10 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
Grade 2 | ASTM B443/B444 Grade 2 material solution-treated at 1093–1204 °C for elevated-temperature service, giving lower strength but greater creep resistance and ductility than the mill-annealed Grade 1. | 330 | 760 | 50 | 170 HB | 1.3 % IACS |
ASTM B443 Grade 2, 1090–1200 °C + rapid cool | Choose for service above ~600 °C where creep resistance and freedom from carbide/δ-phase embrittlement matter more than room-temperature strength. | 390 | 830 | 55 | 165 HB | — |
Hot isostatic pressed | For additive or cast parts needing near-zero porosity and isotropic, fatigue-critical properties (aerospace, subsea). | 450 | 900 | 48 | 175 HB | 1.3 % IACS |
ODefault Annealed | Standard stocked condition for sheet, plate, bar and pipe used below ~600 °C; best combination of strength, ductility and corrosion resistance. | 490 | 930 | 45 | 190 HB | — |
GTAW/GMAW deposit with ERNiCrMo-3 filler, no PWHT | Reference condition for weldments and weld overlays; strength meets base-metal annealed minima without post-weld heat treatment. | 500 | 830 | 35 | 200 HB | 1.3 % IACS |
hot rolled / hot forged, not annealed | Economical condition for heavy bar, forgings and rings that will be machined and heat treated by the customer. | 520 | 940 | 40 | 19 HRC | 1.3 % IACS |
870 °C/1 h (wrought) or 800–900 °C (AM parts) air cool | Use to remove residual stress from cold work, welding or laser powder-bed printing while keeping most of the as-worked/as-printed strength. | 680 | 960 | 35 | 30 HRC | 1.3 % IACS |
laser powder-bed fusion / DMLS, no post heat treatment | Baseline for SLM/DMLS IN625 parts; fine cellular microstructure gives high yield strength but anisotropy and high residual stress. | 720 | 990 | 35 | 30 HRC | — |
Solution annealed + precipitation aged | Pick when maximum room- and mid-temperature strength/hardness is needed (springs, fasteners, downhole tools); ductility and toughness drop. | 860 | 1,200 | 25 | 35 HRC | — |
bar, wire and tube drawn without final anneal | Choose for high-strength wire, springs, fasteners and precision tube where cold-work strengthening replaces heat treatment. | 900 | 1,100 | 20 | 32 HRC | 1.3 % IACS |
What is Inconel 625?
Inconel 625 (UNS N06625, GH3625, 2.4856, NiCr22Mo9Nb) is a solid-solution-strengthened Ni-Cr-Mo-Nb alloy that develops strength from molybdenum and niobium rather than from aging. It pairs a corrosion resistance score of 90 with 490 MPa yield, 930 MPa tensile and 45% elongation, and serves to 650 °C as plate, sheet, pipe and fittings to ASTM B443, bar, and printed parts. It is expensive, hard to machine (score 18) and needs about twice the forming load of 304 stainless; Hastelloy C276 is the step up for hot reducing acids, Inconel 718 when higher strength is required. Inconel 625 has a density of 8.44 g/cm³ (0.305 lb/in³), heavier than 60% of nickel alloy grades. It melts at 1,290°C (2,354 °F). Inconel 625 has a yield strength of 490 MPa (71.1 ksi) and a tensile strength of 930 MPa (135 ksi) — stronger than 71% of nickel alloy grades. Elongation at break is 45% and the elastic modulus is 207.5 GPa (30.1 Msi).
What is Inconel 625 used for?
- Subsea piping and umbilical tubing
- Aerospace exhaust ducts and bellows
- Flue-gas desulfurization components
- Seawater heat exchangers
- Chemical process vessels and pipe spools
- Downhole safety valve components
- Weld overlay and corrosion-resistant cladding
Advantages
- Readily welded — 88/100, better than 92% of nickel alloy grades
- Good corrosion resistance — 90/100, better than 85% of nickel alloy grades
Limitations
- Poor heat conductor — 9.8 W/m·K (5.66 BTU/hr·ft·°F), worse than 92% of nickel alloy grades
Inconel 625 properties
Typical room-temperature values for Inconel 625-O; bars are the position among nickel alloy grades.
Physical3
Inconel 625 has a density of 8.44 g/cm³ (0.305 lb/in³), heavier than 60% of nickel alloy grades. It melts at 1,290°C (2,354 °F).
Mechanical16
Inconel 625 has a yield strength of 490 MPa (71.1 ksi) and a tensile strength of 930 MPa (135 ksi) — stronger than 71% of nickel alloy grades. Elongation at break is 45% and the elastic modulus is 207.5 GPa (30.1 Msi).
Thermal6
Inconel 625 is rated for continuous service to 650°C (1,202 °F). It conducts heat at 9.8 W/m·K (5.66 BTU/hr·ft·°F), worse than 92% of nickel alloy grades. Thermal expansion is 12.8 µm/m·K (7.11 µin/in·°F).
Electrical3
Inconel 625 conducts electricity at 1.3 % IACS, worse than 89% of nickel alloy grades.
Chemical & Environmental3
Corrosion resistance is excellent (90/100), better than 85% of nickel alloy grades.
Sustainability4
Producing a kilogram of Inconel 625 takes about 225 MJ of energy and emits 14 kg of CO₂ — more than 87% of nickel alloy grades. Typical recycled content is 35%.
Manufacturability8
Inconel 625's machinability is poor (18/100, worse than 61% of nickel alloy grades); weldability excellent (88/100); formability very good (70/100).
Common Calculations5
Values are nominal handbook figures for design screening. Certified mill or lot data ships with every FabDigit order on request.
Strength versus weight in the nickel alloy family
Yield strength against density for every nickel alloy grade FabDigit runs. Inconel 625 is highlighted; hover a dot for its name, or open the interactive family chart.
Working with Inconel 625
Is Inconel 625 easy to machine?
Machine like a gummy austenitic superalloy: rigid setups, positive-rake carbide or ceramic tooling, 20–35 m/min with carbide, heavy constant feed to cut under the work-hardened layer, and flood high-pressure coolant.
Can Inconel 625 be welded?
Readily welded by GTAW/GMAW/PAW/laser with ERNiCrMo-3 filler, no preheat and normally no PWHT; keep interpass temperature low, use stringer beads and avoid 650–760 °C dwell to prevent sensitization and knife-line attack.
Can Inconel 625 be formed, bent or molded?
Cold forms well but needs ~2× the press capacity of 304 stainless and frequent intermediate anneals at 980–1040 °C; hot work 950–1200 °C, never in the 760–870 °C range for heavy reductions.
Manufacturability
The process limits FabDigit's quote engine applies to Inconel 625. Design inside these and the part quotes instantly; outside them it routes to an engineer.
CNC machining
| Machinability | Poor18 / 100 |
|---|---|
| ISO material group | S.1 |
| Cutting speed (rough / finish) | 45 / 60 m/min |
| Minimum wall | 1.5 mm |
| Minimum internal radius | 2 mm |
| Drill depth limit | 3× diameter |
| Best surface (machined / polished) | Ra 1.6 / 0.8 µm |
| Hardenable after machining | No |
Sheet metal
| Formability | Fair70 / 100 |
|---|---|
| Weldability | Better88 / 100 |
| Bendable | Yes |
3D printing
| Technologies | DMLS |
|---|---|
| Layer height | 20 – 60 µmdefault 30 µm |
| Minimum wall / feature | 0.5 / 0.3 mm |
| Build envelope | 250 × 250 × 325 mm |
| Supports | Yes |
| Anisotropy | Mild |
| Mandatory post-processing | heat treatment |
Inconel 625 chemical composition (wt %)
Limits by weight percent from the governing specification, written the way the spec states them — a single maximum for impurities, a range for alloying elements, and the base element as balance. Nominal is the typical mid-range value.
| Element | Spec limit (wt %) | Nominal |
|---|---|---|
| Cr | 20 – 23 | 21.5 |
| Mo | 8 – 10 | 9 |
| NbNb+Ta combined | 3.15 – 4.15 | 3.65 |
| Fe | ≤ 5 | 3 |
| Coif determined | ≤ 1 | 0.2 |
| Al | ≤ 0.4 | 0.2 |
| Ti | ≤ 0.4 | 0.2 |
| Mn | ≤ 0.5 | 0.2 |
| Si | ≤ 0.5 | 0.2 |
| C | ≤ 0.1 | 0.05 |
| P | ≤ 0.02 | 0.01 |
| S | ≤ 0.02 | 0.01 |
| Nibalance, min 58 % per ASTM B443/UNS N06625 | ≥ 58 (balance) |
What surface finishes work on Inconel 625?
Pickle/descale in nitric-HF after annealing, then electropolish or mechanically polish; not anodizable — use passivation, glass-bead or electropolished finishes, and grit-blast only with alumina to avoid iron contamination.
Surface treatments FabDigit runs on nickel alloy parts — pick them in the quote configurator or call them out on the drawing. Each links to its datasheet in the surface-finish library (thickness, specs, call-out, material verdicts).
Equivalent designations
Standards and trade names that resolve to Nickel Alloy Inconel 625 in FabDigit's catalog. Equivalence is nominal — check the exact specification when certification matters.
- UNS
- N06625
- ASTM
- B443
- EN / DIN / Werkstoff-Nr.
- 2.4856NiCr22Mo9Nb
- GB (China)
- GH3625
- Also called
- NA21
How much does Inconel 625 cost?
Inconel 625 is a premium-cost nickel alloy ($$$), pricier than about 57% of the materials FabDigit quotes. Part price depends far more on geometry, tolerance and quantity than on the raw stock — upload a CAD file for a live quote.
Inconel 625 — frequently asked
What is Inconel 625 used for?
Inconel 625 is typically used for subsea piping and umbilical tubing, aerospace exhaust ducts and bellows, flue-gas desulfurization components, seawater heat exchangers, chemical process vessels and pipe spools and downhole safety valve components. In short: marine corrosion superalloy.
What is the yield strength of Inconel 625?
Inconel 625 has a typical yield strength of 490 MPa (71.1 ksi) and a tensile strength of 930 MPa (135 ksi) — stronger than 71% of nickel alloy grades. Strength varies by condition: see the 10 listed tempers.
Is Inconel 625 easy to machine?
Not especially — machinability is rated poor (18/100, worse than 61% of nickel alloy grades). Machine like a gummy austenitic superalloy: rigid setups, positive-rake carbide or ceramic tooling, 20–35 m/min with carbide, heavy constant feed to cut under the work-hardened layer, and flood high-pressure coolant.
Can Inconel 625 be welded?
Yes — weldability is rated excellent (88/100). Readily welded by GTAW/GMAW/PAW/laser with ERNiCrMo-3 filler, no preheat and normally no PWHT; keep interpass temperature low, use stringer beads and avoid 650–760 °C dwell to prevent sensitization and knife-line attack.
What surface finishes work on Inconel 625?
Pickle/descale in nitric-HF after annealing, then electropolish or mechanically polish; not anodizable — use passivation, glass-bead or electropolished finishes, and grit-blast only with alumina to avoid iron contamination.
Can Inconel 625 be formed, bent or molded?
Cold forms well but needs ~2× the press capacity of 304 stainless and frequent intermediate anneals at 980–1040 °C; hot work 950–1200 °C, never in the 760–870 °C range for heavy reductions.
What is the maximum service temperature of Inconel 625?
Inconel 625 is rated for continuous use to about 650°C (1,202 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
What is the difference between Inconel 625-O and Inconel 625 Aged?
O is the default condition — standard stocked condition for sheet, plate, bar and pipe used below ~600 °C; best combination of strength, ductility and corrosion resistance. Aged: pick when maximum room- and mid-temperature strength/hardness is needed (springs, fasteners, downhole tools); ductility and toughness drop. Yield strength is 490 MPa in O versus 860 MPa in Aged.
How much does Inconel 625 cost?
Inconel 625 is a premium-cost nickel alloy ($$$), pricier than about 57% of the materials FabDigit quotes. Part price depends far more on geometry, tolerance and quantity than on the raw stock — upload a CAD file for a live quote.
Can FabDigit make parts in Inconel 625?
Yes — Inconel 625 is available for CNC machining, sheet metal and 3D printing with instant online pricing. Upload a STEP file to get a price and a DFM check.
Sources
- ASTM B443 / B444 / B446 — Alloy N06625 plate, sheet, strip, pipe and bar — ASTM International (2019)
- GB/T 15007 / GB/T 15062 — (GH3625/NS3306 ) — SAC (2017)
- INCONEL alloy 625 Publication SMC-063 — Special Metals Corporation (PCC) (2013)
- ASM Handbook Vol. 2 — Properties of Nonferrous Alloys (Ni-base superalloys) — ASM International (1990)
- MMPDS-2023 — Metallic Materials Properties Development and Standardization — Battelle/FAA (2023)
- EOS NickelAlloy IN625 material data sheet (LPBF) — EOS GmbH (2022)
- AWS A5.14 ERNiCrMo-3 filler metal specification — American Welding Society (2018)
Property data is compiled from published supplier and standards handbooks and normalised for comparison; hardness values on non-Brinell scales are converted approximately for charting only. Manufacturability limits are FabDigit quote-engine defaults and may be relaxed by engineering review. Nothing on this page is a certification — request mill certs, CoC or material test reports with your order.