When to pick this combination
L-PBF Inconel 718 is the workhorse for legacy nickel parts that need to survive high temperature, oxidizing environments, and cyclic stress. It is qualified across aerospace OEMs, has the deepest published allowable database in the AM nickel family, and prints reliably on every major L-PBF machine.
Pick this combination when the part operates above 425 °C and below ~650 °C, when fatigue life dominates the design margin, or when the legacy casting drawing already calls for IN718 / AMS 5663.
- Service temperature 425–650 °C
- Fatigue-driven margins (R-ratio ≠ -1)
- Thin internal cooling passages that defeat investment casting
- Low-volume reorders where tooling spin-up is uneconomical
Typical defects and how the model accounts for them
As-built IN718 has 0.3–0.8 % porosity, lack-of-fusion at scan vector transitions, and ~5–10 % strength anisotropy between vertical and horizontal pulls. Residual stress is severe; un-supported overhangs warp.
ForgeCast applies a Walker mean-stress correction to fatigue allowables and widens the uncertainty band based on published scatter (NASA MSFC-STD-3716 and MMPDS-2024 nickel sections). Defect risk in the output reflects the wall thickness, overhang fraction, and aspect ratio of the uploaded geometry.
Required post-processing
The allowables above assume the full post-processing chain. Skipping any step degrades the row above by 15–35 %.
- Stress relief: 1065 °C / 90 min / argon, on the build plate
- EDM or wire-cut from plate
- HIP: 1163 °C / 100 MPa / 4 h
- Solution: 980 °C / 1 h / air cool
- Age: 720 °C / 8 h → 620 °C / 8 h, furnace cool
- Surface finish: machine critical interfaces; AFM or shot-peen flow surfaces
Suggested L-PBF parameters
These are starting parameters for a ~40 µm layer on a 400 W Yb-fiber machine. Always confirm with the OEM build recipe or a parameter qualification coupon.
- Layer thickness: 40 µm
- Laser power: 285 W
- Scan speed: 960 mm/s
- Hatch spacing: 110 µm
- Energy density: ~67 J/mm³
- Build atmosphere: argon, O₂ < 100 ppm
- Pre-heat: 80 °C plate
- Stripe rotation: 67° between layers
Frequently asked questions
Is L-PBF Inconel 718 qualified for flight hardware?
Yes — multiple OEMs (GE, Pratt & Whitney, Rolls-Royce) qualify L-PBF IN718 for non-rotating and selected rotating components. Acceptance always requires a per-part qualification plan; the published allowables are a starting point, not a substitute.
Do I need HIP?
For fatigue-critical parts, yes. Skipping HIP typically drops fatigue life by 5–20×. For static-load parts at low temperature, HIP can sometimes be omitted in favor of a heat-treat-only path, but the part loses ~20 % of its published fatigue allowable.
What is the realistic minimum wall thickness?
0.4 mm is geometrically achievable but fragile and porosity-prone. Use 0.6 mm as a structural minimum and 0.8 mm if the surface will see fluid flow or cyclic load.
Sources
- MMPDS-2024 Chapter 6 (Nickel-base alloys)
- AMS 5663 — Nickel Alloy, Bars/Forgings/Rings, 52.5Ni-19Cr-3Mo-5Cb-0.9Ti-0.5Al-18Fe
- ASTM F3055 — Standard Specification for AM Nickel Alloy (UNS N07718)
- NASA MSFC-STD-3716 — Standard for Additively Manufactured Spaceflight Hardware
- NIST AM Bench 2018 — IN718 single-track and pillar benchmarks