Pick Inconel 718 when strength up to ~700 °C governs; pick Inconel 625 when corrosion, weldability or higher-temperature exposure governs. Both are nickel-based, both print reliably on laser powder beds, and both have their own dedicated AM specification — ASTM F3055 for 718, ASTM F3056 for 625[3][4] — so a PO can demand conformance, not just “nickel alloy”. Here is how the two split.
At a glance
| Property | Inconel 718 | Inconel 625 |
|---|---|---|
| Strengthening mechanism | Precipitation (γ″/γ′) — needs solution + aging | Solid solution (Mo, Nb) — no aging step |
| Typical UTS, as-built/HT | ~1,200–1,380 MPa | ~830–950 MPa |
| Useful strength ceiling | ~650–700 °C | lower stress, but stable higher; oxidation-resistant to ~980 °C |
| Corrosion resistance | Good | Outstanding (PREN ≈ 50 — seawater, acids) |
| Weldability / repair | Printable; controlled HT to avoid strain-age cracking | Excellent — standard weld-overlay alloy |
| AM specification | ASTM F3055 | ASTM F3056 |
| Typical AM parts | Turbine hardware, engine structural, high-strength brackets | Chemical & marine hardware, exhaust/heat components, fixtures |
| Powder cost direction | Baseline | Higher (more Ni, Mo, Nb) |
When 718 wins
718 is the precipitation-hardened workhorse: after solution and aging it reaches the highest room-temperature strength of the two and holds it to roughly 650–700 °C, which is why it dominates turbine and engine-structural applications in both wrought and printed form.[1][5] The trade is heat treatment — printed 718 needs a real solution-plus-two-step-aging schedule (and, for fatigue-critical parts, HIP) to hit the F3055 property table.[6] If your part lives below ~700 °C and strength or fatigue governs the wall thickness, 718 usually buys thinner walls and lighter parts.
When 625 wins
625 skips the aging reaction entirely: molybdenum and niobium in solid solution give it excellent strength with exceptional corrosion resistance — pitting resistance equivalent around 50, which puts it in seawater, acid gas and chemical-process service where 718 would be merely adequate.[2] It is also the better welder and the standard weld-overlay alloy, so printed 625 repairs and integrations onto conventional 625 structures behave predictably. NASA process-comparison work on LPBF 625 documents stable, repeatable builds across full heat-treatment conditions.[7] The bill: higher alloy content makes 625 powder and bar more expensive, and you give up a few hundred MPa of strength versus aged 718.
The decision in one paragraph
High static or fatigue stress below ~700 °C → 718, quoted against ASTM F3055 with the aging schedule named. Corrosive media, seawater, welding onto existing 625, or service that drifts hotter at lower stress → 625, quoted against ASTM F3056. Both run on our powder beds with the full six-stage process — build, stress relief, HIP where specified, finish machining and inspection — and both appear with datasheet-grade chemistry on our materials page. If you are torn between the two, send the loading and the environment; the answer falls out of those two lines.
FAQ
Is Inconel 718 stronger than Inconel 625?
Yes — after solution and aging, printed 718 reaches roughly 1,200–1,380 MPa UTS versus ~830–950 MPa for 625. 625’s advantage is corrosion resistance and high-temperature stability, not strength.[1]
What is the ASTM standard for 3D printed Inconel 718?
ASTM F3055, the powder-bed-fusion specification for nickel alloy UNS N07718; 625 has its own parallel spec, ASTM F3056.[3][4]
Can you weld 3D printed Inconel 625?
Yes — 625 is the standard weldable nickel alloy (widely used for weld overlay), so printed 625 joins and repairs to wrought 625 structures are routine.
Which Inconel for seawater or chemical service?
625. Its PREN of roughly 50 resists pitting and crevice corrosion in chloride media far better than 718.
Send the part — we’ll quote 718, 625 or both →
References
- Carpenter Additive. “PowderRange 718 — Datasheet” (per ASTM F3055). carpenteradditive.com. Link (accessed August 16, 2026).
- Sandvik. “Osprey® Alloy 625 — Powder datasheet.” metalpowder.sandvik. Link (accessed August 16, 2026).
- ASTM F3055-14a. “Standard Specification for Additive Manufacturing Nickel Alloy UNS N07718 with Powder Bed Fusion.” Link (accessed August 16, 2026).
- ASTM F3056-14. “Standard Specification for Additive Manufacturing Nickel Alloy UNS N06625 with Powder Bed Fusion.” Link (accessed August 16, 2026).
- Protolabs. “Inconel 718: A Superalloy with Enduring Relevance.” protolabs.com. Link (accessed August 16, 2026).
- Paulo Products. “Powder Bed Fusion HIP & Heat Treatment: Inconel 718.” paulo.com. Link (accessed August 16, 2026).
- NASA Technical Reports. “In 625 AM Process Comparison — Full Heat Treat.” NTRS, 2022. Link (accessed August 16, 2026).