Inconel 625 (Nickel-Based Superalloy)

Material Profile: Inconel 625 (Nickel-Based Superalloy) for Binder Jetting

Binder Jetting Engineering Material Technical Report Series

Compiled from manufacturer technical datasheets and peer-reviewed literature

Abstract—Inconel 625 (UNS N06625) is a high-performance nickel-chromium-molybdenum-niobium solid-solution-strengthened superalloy and the workhorse Ni-base alloy of metal binder jetting. Qualified across the Desktop Metal Shop System and Production System P-50 (and customer-qualified on X-Series), IN625 combines exceptional cryogenic-to-elevated-temperature strength, outstanding aqueous corrosion resistance (seawater, oxidising acids), and excellent fatigue performance. Unlike IN718, IN625 has no γ' or γ'' precipitation strengthening — it relies entirely on Mo and Nb solid-solution hardening. As-sintered binder-jet IN625 achieves UTS ≈ 760 MPa, yield ≈ 440 MPa, and elongation ≥ 30 %; HIP densification (1150 °C / 100 MPa / 4 h) increases density to ≥ 99.5 % and is mandatory for fatigue-critical aerospace applications. IN625 is exceptionally weldable (no post-weld cracking — in contrast to IN718) and machines comparably to wrought stock, although carbide tooling and slow feed rates are essential.

Index Terms—additive manufacturing, binder jetting, Inconel 625, IN625, nickel superalloy, UNS N06625, Desktop Metal Shop / Production.

I.  MATERIAL IDENTIFICATION

This section establishes the canonical names and commercial designations under which the material is supplied.

A.  Designation

Trade names: Desktop Metal Inconel 625 / IN625; ExOne IN625; Digital Metal DM 625; HP Metal Jet IN625. Wrought equivalents: ASTM B443 / B446 / AMS 5666 (UNS N06625), Inconel® 625 (Special Metals registered trademark), Nicrofer 6020 hMo. AM-specific specification: ASTM F3056-14e1 (powder-bed fusion N06625).

B.  Full Chemical Name

Nickel-chromium-molybdenum-niobium solid-solution strengthened superalloy. Composition (wt%): Ni ≥ 58 (balance), Cr 20.0–23.0, Mo 8.0–10.0, Nb (+Ta) 3.15–4.15, Fe ≤ 5.0, Co ≤ 1.0, Mn ≤ 0.5, Si ≤ 0.5, Al ≤ 0.4, Ti ≤ 0.4, C ≤ 0.10, P ≤ 0.015, S ≤ 0.015. Single-phase FCC γ-Ni matrix; primary strengthening through Mo and Nb solute atoms; no precipitation hardening (unlike IN718).

C.  Aliases and Alternative Designations

II.  COMPOSITION AND MOLECULAR STRUCTURE

A.  Empirical Chemical Formula

Ni(balance, ≥ 58%) — Cr(20–23%) — Mo(8–10%) — Nb+Ta(3.15–4.15%) — Fe(≤5%) — minor (Co, Mn, Si, Al, Ti, C). FCC γ-Ni matrix with substantial solid-solution strengthening from Mo and Nb. No γ' or γ'' precipitates (no aging hardening response).

Fig. 1.  Repeating unit / structural schematic of the polymer matrix.

Fig. 2.  Schematic of the single-phase polymer (no reinforcement).

B.  Composition Breakdown

TABLE I
 COMPOSITIONAL BREAKDOWN OF INCONEL 625 (DESKTOP METAL SHOP / PRODUCTION) (TYPICAL / PER SUPPLIER DATASHEET)

III.  MECHANICAL PROPERTIES — XY BUILD DIRECTION (HORIZONTAL)

In the XY orientation the tensile load is applied parallel to the powder-bed plane. Binder-jetted (BJ) parts in the as-sintered state generally show modest in-plane vs build-axis anisotropy because sintering occurs near the solidus and re-distributes the porosity left by the binder-removal step. For metal BJ, post-sintering treatments (HIP, solution-anneal, age) are commonly applied to bring properties to wrought-equivalent and to eliminate residual closed porosity.

TABLE II
 MECHANICAL PROPERTIES — XY ORIENTATION (INCONEL 625 (DESKTOP METAL SHOP / PRODUCTION))

IV.  MECHANICAL PROPERTIES — Z BUILD DIRECTION (VERTICAL)

In the Z orientation the tensile load is applied perpendicular to the printed layers. Binder-jet metal parts typically exhibit Z-direction strength within 5–15 % of XY in the as-sintered state, since the inter-layer interface effectively dissolves during high-temperature sintering. For sand-mould materials, Z-direction strength is dominated by inter-layer binder bonding and is generally 60–90 % of XY in transverse strength.

TABLE III
 MECHANICAL PROPERTIES — Z ORIENTATION (INCONEL 625 (DESKTOP METAL SHOP / PRODUCTION))

Binder-jet IN625 has very low anisotropy (~3 % UTS difference) because the high-sinter temperature (~1300 °C) and slow cooling redistribute the FCC γ-Ni grain structure uniformly. HIP at 1150 °C / 100 MPa / 4 h is mandatory for fatigue-critical aerospace components — closes residual microporosity and dramatically improves high-cycle fatigue life. Solution annealing at 1095 °C / 1 h is recommended for parts that will be welded.

V.  RECOMMENDED PROCESS PARAMETERS

Values summarised below give consensus operating windows from public datasheets (Desktop Metal, ExOne, voxeljet, cprint3d). Specific machines and parameter sets may differ within ±10 %; the supplier's verified parameter sheet always supersedes this table. For metal binder jetting, complete green-state cure (~200 °C) and a high-temperature de-bind / sinter cycle (typically 1 100–1 380 °C in H₂ / Ar / vacuum) are mandatory after print. For sand binder jetting, parts are usable directly after print (with optional microwave or oven post-cure).

TABLE IV
 RECOMMENDED BINDER-JETTING PROCESS PARAMETERS FOR INCONEL 625 (DESKTOP METAL SHOP / PRODUCTION)

VI.  GLASS TRANSITION TEMPERATURE (TG)

Reported / typical Tg: Not applicable (metallic alloy).

Critical thermal limits: continuous service temperature ~ 980 °C (oxidation-limited); useful strength to ~ 815 °C; carbide precipitation window 540–760 °C (Cr₂₃C₆, M₆C — minor effect on 625 unlike sensitisation in stainless steels); melting range 1290–1350 °C (note: only ~30 °C between solidus and sinter temperature — narrow process window).

VII.  HEAT DEFLECTION TEMPERATURE (HDT)

Heat deflection temperature is the temperature at which a standard bar deflects 0.25 mm under a specified flexural load (ASTM D648 / ISO 75).

TABLE V
 HEAT DEFLECTION TEMPERATURE OF INCONEL 625 (DESKTOP METAL SHOP / PRODUCTION) UNDER STANDARD TEST LOADS

VIII.  DISTINGUISHING CHARACTERISTICS AND STANDARDS

A.  Best-in-class corrosion resistance

IN625 resists pitting, crevice, and stress-corrosion cracking in seawater, hot acids, and most oxidising media. Pitting Resistance Equivalent Number (PREN) ≈ 51 — vs ~26 for 316L. The benchmark alloy for offshore oil/gas and chemical-handling applications.

B.  Cryogenic to high-temperature service

Useful from –196 °C (LN₂) to ~ 815 °C — the widest temperature envelope of any binder-jettable metal. No ductile-to-brittle transition (unlike low-alloy steels) — preferred for cryogenic LNG fittings and aerospace cryogenic propellant systems.

C.  Exceptional weldability

Unlike IN718 (which suffers post-weld strain-age cracking), IN625 is essentially crack-free after welding because solid-solution strengthening does not require an aging step. Filler metal AMS 5837 (ER NiCrMo-3) provides matched composition welds.

D.  No aging hardening — predictable properties

Properties are stable across all heat-treatment conditions; service exposure does not significantly alter strength (unlike IN718 which softens above 760 °C from γ'' coarsening). Specifications-engineering simplification — single-state material spec covers all life-cycle conditions.

E.  Higher cost, longer sinter cycle

IN625 powder cost is ~3× 316L; sinter cycle requires careful temperature control (only 30 °C margin to solidus) and longer hold times. For lower-cost applications, 316L or 4140 should be evaluated first; IN625 is justified when corrosion resistance, high-temperature performance, or weldability are operationally critical.

IX.  REPRESENTATIVE APPLICATIONS

Inconel 625 (Desktop Metal Shop / Production) is typically deployed in the following applications:

1)  Aerospace turbine and engine components: Combustor liners, exhaust systems, bellows, seal segments — high-temp + thermal-cycle resistance.

2)  Marine and offshore hardware: Pump impellers, seawater heat exchanger tube sheets, subsea connectors — chloride pitting/crevice immunity.

3)  Chemical processing equipment: Reactor internals, heat exchanger tubes, valve bodies in oxidising acids (HNO₃, H₂SO₄ at moderate concentrations).

4)  Oil & gas downhole tools: Wellhead components, MWD tools, sour-service (H₂S-bearing) hardware — NACE MR0175 / ISO 15156 compliance achievable.

5)  Nuclear and power generation: Steam generator tubes, control rod components, balance-of-plant fittings — high creep resistance + radiation tolerance.

X.  REFERENCES

[1]  Desktop Metal, “Inconel 625 — Material Data Sheet,” 2024.

[2]  Desktop Metal, “Desktop Metal Qualifies Nickel Alloy Inconel 625 for Studio System 2,” Press release, 2022. [Online]. Available: https://ir.desktopmetal.com/news/press-releases/detail/118/

[3]  ASTM B443-22, “Standard Specification for Nickel-Chromium-Molybdenum-Columbium Alloy Plate, Sheet, and Strip,” 2022.

[4]  ASTM B446-22, “Standard Specification for Nickel-Chromium-Molybdenum-Columbium Alloy Rod and Bar,” 2022.

[5]  ASTM F3056-14e1, “Standard Specification for Additive Manufacturing Nickel Alloy (UNS N06625) with Powder Bed Fusion,” 2014.

[6]  AMS 5666N, “Nickel Alloy, Corrosion- and Heat-Resistant, Bars, Forgings, and Rings — 62Ni-21.5Cr-9.0Mo-3.6Cb,” SAE International.

[7]  Special Metals Corporation, “INCONEL® alloy 625 — Technical Bulletin,” Publication SMC-066, 2013.

[8]  ASTM E8/E8M-22, “Standard Test Methods for Tension Testing of Metallic Materials,” ASTM International, 2022.

[9]  ASTM B962-17, “Standard Test Methods for Density of Compacted or Sintered Powder Metallurgy (PM) Products Using Archimedes' Principle,” ASTM International, 2017.

[10]  ASTM E18-22, “Standard Test Methods for Rockwell Hardness of Metallic Materials,” ASTM International, 2022.

[11]  ASTM F3318-22, “Standard for Additive Manufacturing — Finished Part Properties — Specification for AlSi10Mg with Powder Bed Fusion — Laser Beam,” ASTM International, 2022.

[12]  ISO/ASTM 52900:2021, “Additive manufacturing — General principles — Fundamentals and vocabulary,” ISO, 2021.

[13]  ISO/ASTM 52904:2024, “Additive manufacturing — Process characteristics and performance — Practice for metal powder bed fusion process to meet critical applications,” ISO, 2024.

[14]  MPIF Standard 35-MIM, “Materials Standards for Metal Injection Molded Parts,” Metal Powder Industries Federation, 2022 ed.

[15]  Desktop Metal, “Material Properties of Binder Jet Parts,” Desktop Metal Technical White Paper. [Online]. Available: https://www.desktopmetal.com/resources/material-properties-of-binder-jet-parts

[16]  Desktop Metal, “Why Binder Jetting?” Desktop Metal Application Note. [Online]. Available: https://www.desktopmetal.com/resources/why-binder-jetting-1

[17]  Desktop Metal, “Materials portfolio overview,” Desktop Metal product page. [Online]. Available: https://www.desktopmetal.com/materials/

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