CP-Ti Grade 4
metaltitanium — commercially pure alpha
CP Titanium Grade 4Grade 4 TiASTM F67 Grade 4ISO 5832-2 Grade 4Ti Grade 4Commercially Pure Titanium Grade 4
Composition — ASTM F67 Grade 4 / ISO 5832-2 / ASTM B265 Grade 4 — commercially pure Ti with max 0.4 wt% O
| Element | Min % | Max % | Notes |
|---|---|---|---|
| Ti | — | — | balance — single-phase alpha microstructure; no beta stabilisers |
| O | — | 0.400 | Oxygen is the primary strengthening interstitial — max 0.40 wt% (higher than Grade 2: 0.25%). O solid-solution strengthens alpha phase significantly |
| Fe | — | 0.500 | Iron — max 0.50 wt%; higher Fe than Grade 2 (0.30%) contributes to solid-solution strengthening; also mild beta stabiliser but insufficient to form two-phase microstructure |
| N | — | 0.050 | Nitrogen interstitial — strengthens but reduces ductility at higher levels; controlled to max 0.05 wt% |
| C | — | 0.080 | Carbon impurity — forms TiC if excessive; controlled to max 0.08 wt% |
| H | — | 0.015 | Hydrogen impurity — hydride formation degrades ductility; strict maximum 0.015 wt% (150 ppm); critical to control during AM powder handling |
Mechanical & thermal properties — 3 conditions
| Property | LPBF as-built (XY) | LPBF annealed 700°C/2h (XY) | EBM as-built (XY) |
|---|---|---|---|
| Elastic modulus | 100–107 GPa | 103 GPa | 98–106 GPa |
| Yield strength (0.2%) | 500–610 MPa | 440–530 MPa | 460–550 MPa |
| Ultimate tensile strength | 600–720 MPa | 540–630 MPa | 565–660 MPa |
| Elongation at break | 12.0–20.0 % | 18.0–28.0 % | 14.0–23.0 % |
| Hardness (HV) | 200–245 HV | 175–210 HV | 185–220 HV |
| Density | 4.51 g/cm³ | 4.51 g/cm³ | 4.50 g/cm³ |
Values shown as min–max where a spread is reported, otherwise as typical ± unit. Ranges reflect inter-source variation, not single-sample scatter. All values are for AM-processed specimens unless noted.
Engineering considerations
- Medical qualification: AM CP-Ti Grade 4 implants require compliance with ASTM F67 (or ISO 5832-2) chemical limits AND minimum mechanical properties. LPBF or EBM process qualification must follow a framework such as ASTM F3001 (Ti-6Al-4V) adapted for CP-Ti, or the manufacturer's validated process. Each implant design may require design-specific testing.
- Grade 4 vs Grade 2 selection: Grade 2 (CP_TI_GR2) offers higher ductility (30%+ elongation) and better corrosion resistance at the cost of lower strength (YS ~380–430 MPa). Specify Grade 4 when strength ≥480 MPa YS is required; Grade 2 when maximum ductility and corrosion resistance outweigh strength needs.
- Grade 4 vs Ti-6Al-4V selection: Grade 4 is preferred when (1) vanadium-free alloy is mandated; (2) superior corrosion resistance is needed; (3) higher ductility is required (surgical contouring, impact). Use Ti-6Al-4V when strength >700 MPa is needed.
- Hydrogen control: Titanium is highly susceptible to hydrogen embrittlement. Build in vacuum (EBM) or inert argon (LPBF with <50 ppm O₂, <10 ppm H₂O). Store powder sealed; never re-use powder exposed to moisture without re-certification. Post-build, anneal in vacuum to degas — do not anneal in hydrogen-containing atmospheres.
- EBM vs LPBF for medical: EBM's vacuum environment eliminates atmospheric contamination risk and delivers lower residual stresses, making it attractive for implants. However, LPBF offers finer feature resolution and better surface finish — important for complex porous scaffold geometries used in osseointegration implants.
- Annealing protocol: 700°C/2h in vacuum (<1×10⁻³ mbar) or argon (<10 ppm O₂) is standard. Do not anneal above 900°C (beta transus ~890°C for Grade 4) — beta phase transformation degrades ductility on cooling.
- Osseointegration design: Porous surface structures (trabecular, gyroid lattice) promote bone ingrowth. Minimum pore size for osseointegration: 100–400 µm; optimal ~300 µm. Verify strut resolution capability with your machine and parameters — EBM typically achieves ≥400 µm features; LPBF can resolve ≥200 µm.
Advantages
- 100% corrosion resistant in seawater, chloride media, and nitric acid — superior to Ti-6Al-4V which has slight susceptibility to crevice corrosion in some conditions
- Biocompatible and osseointegratable — ISO 10993 compliant; well-established clinical track record in dental and orthopaedic applications
- No vanadium — preferred in regulatory regimes concerned about V ion release (V is cytotoxic at high concentrations)
- Better ductility than Ti-6Al-4V (22% vs 8–10% elongation annealed) — clinically significant for intraoperative contouring of bone plates
- Simpler post-build heat treatment than Ti-6Al-4V: 700°C/2h anneal is sufficient; no solution annealing or ageing required
- EBM as-built condition already meets ASTM F67 minimums — may eliminate separate annealing step
- Lower oxygen sensitivity in AM than Grade 1/2 (max 0.4 wt% O) — more process-tolerant atmosphere requirements
Limitations
- Lower strength than Ti-6Al-4V (~550–650 MPa UTS vs ~900–1000 MPa) — not suitable for high-load structural aerospace or motorsport applications
- No precipitation hardening or ageing pathway — strength cannot be increased by heat treatment beyond as-built
- Higher cost and lower availability than Ti-6Al-4V powder for AM — fewer qualified powder suppliers
- LPBF parameter development is less mature than Ti-6Al-4V — fewer published process envelopes and fewer machine OEM qualified parameter sets
- Hydrogen contamination risk during AM and post-processing — requires strict atmosphere control and vacuum annealing to keep H <150 ppm; hydrogen embrittlement is catastrophic in Ti
- Not suitable for high-temperature structural use (>350°C creep onset) — use Ti-6Al-2Sn-4Zr-2Mo or Ti-6242 for elevated temperature
Typical applications
Medical implants where alpha-Ti microstructure is preferred over Ti-6Al-4V (e.g. when vanadium-free alloy is mandated)Dental frameworks and crowns requiring high biocompatibility and osseointegrationMarine hardware: valves, fasteners, pump components in seawaterChemical processing equipment exposed to corrosive media (HNO₃, Cl⁻ environments)Heat exchangers for corrosive fluids (desalination, chemical plants)Orthopaedic bone plates and screws where high ductility is preferred for contouring in surgeryCryogenic components (CP-Ti maintains ductility at cryogenic temperatures)
Industries
medicaldentalindustrialoil-gasenergy
Standards & certifications
ASTM-F67-13established
Standard specification for unalloyed titanium for surgical implant applications (Grade 4 is the highest-strength grade)
medicaldental
Primary standard for CP-Ti medical implants. LPBF/EBM parts must meet chemical composition and minimum mechanical property requirements. AM parts may require additional process qualification per ASTM F3001 or ISO 22674.
ISO-5832-2established
Implants for surgery — metallic materials — unalloyed titanium (ISO equivalent of ASTM F67)
medicaldental
European/international equivalent of ASTM F67. Required for CE-marked medical devices in EU and UK.
Compatible AM processes (2)
Other metal materials
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Related calculators
LPBF Porosity PredictorPredict lack-of-fusion and keyhole porosity from laser parameters. Maps VED and normalised enthalpy to relative density and flags dangerous regimes.Powder Characterisation TrackerScore a powder batch against key qualification metrics — particle size distribution, flowability, apparent/tap density, moisture, and oxygen content.NDT SelectorSelect the right non-destructive testing method for your AM part. Inputs: material class, defect focus, geometry, production volume, and criticality. Ranked scorecard across CT, X-ray, UT, FPI, MPI, eddy current, and visual inspection with detection limits and standard references.HT AdvisorStandard stress-relief, solution, and aging cycles for AM metals (Ti-6Al-4V, IN718, 17-4PH, AlSi10Mg, 316L, CuCrZr) per AMS, ASTM F3301, and AMS 5664.FatigueS-N curve estimation for AM metals using the Basquin law. Accounts for surface roughness stress concentration (Kt from Ra), build direction anisotropy, and porosity factor.RoughnessTheoretical Ra and Rz from layer thickness and surface angle (staircase effect). Upward, downward, and vertical faces. LPBF, SLS, FDM, SLA, DED. Per Grimm et al.
Last reviewed: 2026-05-15 · v1 · Sources: yang-2019-cpti-gr4, murr-2012-cpti-ebm, petzow-1988-ti-handbook
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