Inconel 625

metal

nickel superalloy — solid-solution-strengthened

UNS N06625Alloy 625IN625Nicrofer 6020 hMoHaynes 625AMS 5666 (wrought ref.)

Density

8.44 g/cm³

YS (LPBF as-built (XY))

540–680 MPa

UTS (LPBF as-built (XY))

820–980 MPa

Elongation (LPBF as-built (XY))

25.0–48.0 %

Elastic modulus

195–215 GPa

Thermal conductivity

9.8 W/m·K

Composition — UNS N06625 / ASTM F3056-14

Element	Min %	Max %	Notes
Ni	58.00	—	balance. High Ni for corrosion resistance in reducing acids
Cr	20.00	23.000	Cr₂O₃ scale — oxidation and high-temperature corrosion resistance
Mo	8.00	10.000	Primary solid solution strengthener; pitting and crevice corrosion resistance in seawater
Nb	3.15	4.150	Solid solution strengthening; also forms Laves phase and δ (delta) during LPBF thermal cycling
Fe	—	5.000

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Mechanical & thermal properties — 4 conditions

Property	LPBF as-built (XY)	LPBF as-built (Z)	LPBF stress-relieved (XY)	LPBF solution-annealed (isotropic)
Elastic modulus	195–215 GPa	—	—	—
Yield strength (0.2%)	540–680 MPa	470–600 MPa	520–650 MPa	390–490 MPa
Ultimate tensile strength	820–980 MPa	730–880 MPa	790–940 MPa	720–850 MPa
Elongation at break	25.0–48.0 %	20.0–42.0 %	28.0–50.0 %	40.0–60.0 %
Hardness (HV)	250–320 HV10	—	—	200–245 HV10
Fatigue strength	370–490 MPa	—	—	—
Density	8.44 g/cm³	—	—	—
Thermal conductivity	9.8 W/m·K	—	—	—
CTE	12.6–13.6 µm/m·K	—	—	—

Values shown as min–max where a spread is reported, otherwise as typical ± unit. Ranges reflect inter-source variation, not single-sample scatter. All values are for AM-processed specimens unless noted.

Engineering considerations

Post-processing selection: as-built (highest strength, Laves present) vs stress-relieved (balanced) vs solution-annealed (maximum ductility, corrosion, and isotropic properties). Oil & gas typically uses stress-relieved; subsea structural uses solution-annealed.
NACE sour service: ISO 15156-3 (NACE MR0175) qualifies solution-annealed LPBF IN625 for H₂S-containing environments. Verify hardness ≤40 HRC (≈388 HV) — as-built LPBF typically passes.
Distortion control: IN625 has even lower thermal conductivity than IN718 — larger parts require simulation-based distortion compensation before build. Mandatory stress-relief before removal from plate.
DED cladding: LPBF IN625 is used for near-net-shape parts; DED IN625 is the dominant process for corrosion-resistant overlays on carbon and low-alloy steel (API 6A, NACE HIC-resistant). DED achieves 2–4 mm/h deposition on large surfaces.
Anisotropy reduction: solution anneal at 1150°C recrystallises columnar grains and makes properties near-isotropic. Required when design assumes isotropic material (common in pressure vessel codes).
Cryogenic service: solution-annealed LPBF IN625 retains excellent ductility and fracture toughness at -196°C — suitable for LNG valves, pump housings, and manifolds.
Oxidation protection: IN625 is protected to ~980°C by Cr₂O₃ scale. Above 1000°C, protective scale becomes unstable — use wrought IN625 forging or cast IN713 for higher temperatures.
Powder re-use: Mo and Nb are heavy elements that segregate to powder surfaces with thermal cycling. Monitor chemistry carefully — limit re-use to 20–25 cycles without blending to virgin.

Advantages

Outstanding corrosion resistance across an extremely wide range of environments: oxidising, reducing, seawater, chloride, acids
No complex post-heat-treatment required — as-built or stress-relieved meets most structural and corrosion requirements
Good strength and ductility maintained from cryogenic temperatures (-196°C) to ~815°C
Pitting resistance equivalent number (PREN) ~52 — far exceeds super-duplex stainless (~43)
NACE MR0175 / ISO 15156-3 qualified for sour-service (H₂S-containing) environments
Excellent resistance to sensitisation — no age-hardening means no Cr-depletion risk
DED/WAAM IN625 is the leading cladding alloy for offshore and chemical industry repair
Good weldability with IN625 or IN82 filler wire

Limitations

No precipitation hardening — cannot approach IN718 or CoCrMo strength levels (max YS ~700 MPa as-built)
Very low thermal conductivity (9.8 W/m·K) — highest residual stress accumulation of LPBF nickel alloys; support and scan strategy critical
Laves phase in as-built condition reduces ductility and creep resistance vs. wrought annealed
High density (8.44 g/cm³) — heaviest common AM metal after CoCrMo
Elevated cost relative to stainless steel — justify with genuine corrosion or temperature requirement
LPBF fatigue database is sparse vs. IN718 — conservative design factors needed for cyclic-loaded components
δ-phase precipitation between 650–980°C — if stress-relief temperature is too low, δ-phase can reduce ductility
Mo-rich Laves phase at grain boundaries reduces sour-service corrosion resistance unless dissolved by solution anneal

Typical applications

Subsea wellhead components and riser clampsHeat exchanger tubing for aggressive chemical environmentsFuel nozzles and combustor liners (aerospace)Exhaust system components for marine gas turbinesChemical reactor vessels and piping (strong acids, halides)Cryogenic LNG vessel hardware and fittingsFlare tips and high-temperature exhaust componentsCorrosion-resistant overlays via DED on carbon steel componentsNuclear waste handling fixturesDeep-sea instrumentation housings

Standards & certifications

ASTM-F3056established

IN625 (UNS N06625) parts produced by powder bed fusion — composition, powder, and minimum mechanical property requirements

aerospaceenergyindustrial

YS ≥345 MPa, UTS ≥690 MPa, El ≥25% minimum. Deliberately conservative — LPBF IN625 typically exceeds by 50–100%.

ISO-52904established

Process quality assurance for safety-critical PBF parts

aerospaceenergy

AMS-7000established

LPBF process requirements for aerospace production

aerospacedefence

ASTM-E8established

Tensile test method for acceptance testing

aerospaceenergyindustrial

Inconel 625

Composition — UNS N06625 / ASTM F3056-14

Mechanical & thermal properties — 4 conditions

Engineering considerations

Advantages

Limitations

Typical applications

Industries

Standards & certifications

Compatible AM processes (5)

Other metal materials

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