When to pick this combination
Binder jetting wins on unit economics: powder is jetted with a liquid binder, then the green part is sintered in a furnace. No lasers, no per-part scan time — the build is volumetric. For batches of dozens to hundreds, BJT 17-4 PH lands 3–6× cheaper than L-PBF.
Pick this combination when you have a legacy investment-cast or MIM part, the geometry is dimensionally forgiving (sinter shrinkage is ~20 %), and the operating environment is below 315 °C in a mildly corrosive medium.
- Brackets, housings, fittings produced in batches of 50+
- Replacements for legacy MIM or investment castings
- Parts where unit cost dominates over absolute fatigue margin
Typical defects and how the model accounts for them
Sintered BJT 17-4 PH carries 1–3 % residual porosity even after HIP, distributed as small spherical pores. Density is 95–99 % of wrought. Sinter shrinkage is non-uniform: thin sections shrink more than thick sections, leading to dimensional drift on cantilevered features.
ForgeCast scales the fatigue allowable down by ~20 % vs wrought H900 and flags any unsupported cantilever > 25 mm as a dimensional-risk feature.
Required post-processing
The sinter cycle is the single biggest cost and risk driver. HIP closes residual porosity but does not fix sinter distortion.
- Cure green part: 200 °C / 4 h in air
- Depowder, support-free
- Sinter: 1370 °C / 6 h / H₂ atmosphere
- Optional HIP: 1150 °C / 100 MPa / 3 h (closes pores, recovers ~10 % fatigue)
- Solution: 1040 °C / 30 min / oil quench
- Age H900: 482 °C / 1 h / air cool
- Surface: as-sintered Ra ~6 µm; tumble or bead-blast critical surfaces
Suggested BJT parameters
Build parameters are OEM-specific (HP MetalJet, Desktop Metal Production System, ExOne). The sinter recipe matters more than the print recipe.
- Layer thickness: 50 µm
- Binder saturation: 60–80 %
- Print speed: ~3000 cm³/hr (machine-volumetric)
- Green strength: handle with care, MOR ~5 MPa
- Sinter shrinkage: ~20 % linear, anisotropic ±2 %
Frequently asked questions
How does BJT 17-4 PH compare to wrought H900?
After HIP and H900 age, sintered BJT 17-4 PH reaches ~95 % of wrought UTS and ~80 % of wrought fatigue. The gap is dominated by residual porosity, not microstructure.
How much shrinkage compensation do I need?
~20 % linear, but it varies by section thickness. Apply a uniform scale factor in the build prep, then run a first-article inspection on critical features and iterate the per-axis scale. Plan for one DOE cycle on geometry-sensitive parts.
Is binder jetting good for fatigue-critical parts?
Only with HIP. As-sintered fatigue is ~20 % below wrought; HIP closes the gap to ~15 %. For high-cycle aerospace-class fatigue use L-PBF or DMLS instead.
Sources
- ASTM A564 / A564M — Hot-Rolled and Cold-Finished Age-Hardening Stainless Steel
- AMS 5643 — 17-4 PH Bars, Forgings, Rings (H900 condition)
- MPIF Standard 35 — Materials Standards for Metal Injection Molded Parts (reference for sintered comparable)
- ASTM F3413 — Guide for Additive Manufacturing — Design — Directed Energy Deposition