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Laser Powder Bed Fusion (L-PBF) · Ti-6Al-4V Grade 23 (ELI)

L-PBF Ti-6Al-4V

Aerospace-grade titanium printed by laser powder bed fusion. Highest strength-to-weight in the AM titanium family, with the deepest qualification record.

Allowables
UTS950 – 1100MPa
Yield860 – 990MPa
Elongation10 – 18%
Fatigue (R = -1, 10⁷)350 – 510MPa
Density4.43g/cm³

Condition: HIP + stress-relief (per ASTM F3001)

When to pick this combination

L-PBF Ti-6Al-4V is the default for weight-critical structural parts: brackets, manifolds, fuel-system housings, and patient-specific orthopedics. It is qualified to ASTM F3001 (ELI) and ASTM F2924 (standard) and has the widest published allowable database of any AM titanium grade.

Pick this combination when mass matters, the service environment is below ~315 °C, or when corrosion resistance and biocompatibility are part of the spec.

  • Aerospace structural brackets and housings
  • Topology-optimized parts where mass dominates cost
  • Marine and chemical exposure
  • Medical implants (with separate FDA pathway)

Typical defects and how the model accounts for them

As-built Ti-6Al-4V has 0.2–0.5 % porosity, gas pores from atomization-trapped argon, and a strongly columnar prior-β grain structure. Strength anisotropy is 8–12 % between Z and XY pulls. Oxygen pickup above 0.2 wt% embrittles the part — atmosphere control is non-negotiable.

ForgeCast widens the fatigue band more aggressively than for nickel: Ti-6Al-4V AM fatigue scatter is dominated by surface roughness and sub-surface porosity, both of which respond to HIP. Defect risk scales sharply with overhang fraction.

Required post-processing

Skipping HIP costs about 30 % of fatigue life on Ti-6Al-4V — more than on IN718. Surface finish dominates the residual scatter.

  • Stress relief: 800 °C / 2 h / argon on plate
  • Wire-EDM from plate
  • HIP: 920 °C / 100 MPa / 2 h
  • Surface: machine critical features; chemical mill or AFM for flow surfaces
  • Optional: alpha-case removal if any open-air thermal exposure occurred

Suggested L-PBF parameters

Starting parameters for a 30 µm layer on a 400 W Yb-fiber machine. Hatch rotation and contour passes have a disproportionate impact on Ti-6Al-4V fatigue — do not skip them.

  • Layer thickness: 30 µm
  • Laser power: 280 W
  • Scan speed: 1200 mm/s
  • Hatch spacing: 140 µm
  • Energy density: ~55 J/mm³
  • Build atmosphere: argon, O₂ < 50 ppm
  • Pre-heat: 200 °C plate (reduces residual stress)
  • Contour: 2 passes at 100 W / 800 mm/s

Frequently asked questions

Grade 5 or grade 23 (ELI)?

ELI (extra-low-interstitial) ships with tighter O, N, and Fe limits and gives the best fatigue and fracture toughness — use it for any cyclic-load structural application. Grade 5 is acceptable for static-load brackets where cost dominates.

Why is the fatigue range so wide?

AM Ti-6Al-4V fatigue is driven by surface roughness and sub-surface porosity, not bulk microstructure. As-built rough surfaces sit near 350 MPa; machined and HIP'd surfaces approach wrought 510 MPa. The band reflects that gap.

Can I use EBM instead?

EBM gives lower residual stress and higher build rate, at the cost of coarser finish and resolution. For large monolithic parts EBM often wins. For thin walls (< 0.8 mm) or fine features, L-PBF is the better choice.

Sources

  1. MMPDS-2024 Chapter 5 (Titanium alloys)
  2. ASTM F3001 — Standard Specification for AM Ti-6Al-4V ELI
  3. ASTM F2924 — Standard Specification for AM Ti-6Al-4V
  4. NASA MSFC-STD-3716
  5. AWS D20.1 — Specification for Fabrication of Metal Components using AM

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Related

Process page
DMLS Ti-6Al-4V

EOS-style direct metal laser sintering of titanium. Functionally identical to L-PBF, with deep OEM parameter qualification and an exceptionally wide installed base.

Process page
EBM Ti-6Al-4V

Vacuum electron-beam melting of titanium. Lower residual stress and higher build rate than L-PBF, at coarser resolution. The default for monolithic Ti structures and orthopedic implants at volume.

Process page
L-PBF AlSi10Mg

The default aluminum for laser powder bed fusion. Light, weldable, thermally conductive — the workhorse for housings, heat exchangers, and topology-optimized brackets where mass matters more than absolute strength.

Note
Applying the Walker mean-stress correction to AM fatigue data

A practical walk-through of choosing γ, scaling R-ratio-shifted S-N data, and avoiding the most common Walker misuses on AM-built coupons.

Note
HIP vs as-built: when post-processing pays back

HIP roughly doubles the fatigue allowable on L-PBF Ti and nickel — but only if your defect mode is gas porosity. Here is when it doesn't.

Note
Why AM fatigue scatter is bigger than wrought, and how to plan for it

Defect populations, surface state, and build location each contribute. Here is how each one shows up in the S-N data and what to do about it.

Note
Build orientation and anisotropy in L-PBF allowables

Columnar grains aligned with the build direction make Z-pulls 5–15% weaker in UTS and up to 30% weaker in fatigue. Here's how to design around it.

Note
Powder reuse and oxygen pickup: keeping AM feedstock in spec

Each build leaves residual oxygen in the unmelted powder. Past a per-alloy threshold, mechanical properties collapse before density does.

Note
Support strategy economics: when supports cost more than the part

On many real parts the support strategy is half the total cost. Self-supporting redesign usually pays back inside the first build.

Comparison
EBM vs L-PBF for Ti-6Al-4V

EBM wins on residual stress and bulk Ti throughput; L-PBF wins on surface finish, feature resolution, and broader OEM availability.