R56700 is an alpha-beta titanium alloy developed specifically for surgical implant applications. This datasheet presents the material within the American (ASTM / ASME / UNS) standard system.
Developed as an alternative to Ti-6Al-4V, R56700 replaces vanadium with about 7% niobium to avoid the potential biological concerns associated with vanadium, while retaining mechanical properties close to those of Ti-6Al-4V (Grade 5). The aluminium stabilises and strengthens the alpha phase while the niobium stabilises the beta phase, giving a two-phase alpha-beta microstructure with high specific strength, good fatigue strength, a relatively low elastic modulus and excellent corrosion resistance. Its outstanding biocompatibility, established under ASTM F1295, has made it a preferred material for load-bearing orthopedic and dental implants. It is normally used in the annealed condition.
Typical applications include hip and knee prostheses, bone plates, screws and nails, spinal and trauma implants, and dental implant components.
| Property | Value | Unit |
|---|---|---|
| Density | 4.52 | g/cm³ |
| Beta transus | 1010 | °C |
| Elastic modulus | 105 | GPa |
| Coefficient of thermal expansion (20–100 °C) | 8.5 | µm/m·°C |
| Thermal conductivity (20 °C) | 7.0 | W/m·K |
| Specific heat (20 °C) | 523 | J/kg·K |
| Structure | Alpha-beta | — |
| Element | Symbol | Min % | Max % | Role in Alloy |
|---|---|---|---|---|
| Titanium | Ti | Balance | — | Base element |
| Aluminium | Al | 5.50 | 6.50 | Alpha stabiliser; strength |
| Niobium | Nb | 6.50 | 7.50 | Beta stabiliser; biocompatibility |
| Tantalum | Ta | — | 0.50 | Residual |
| Iron | Fe | — | 0.25 | Residual |
| Oxygen | O | — | 0.20 | Interstitial; strength |
| Carbon | C | — | 0.08 | Interstitial impurity |
| Nitrogen | N | — | 0.05 | Interstitial impurity |
| Hydrogen | H | — | 0.009 | Interstitial impurity |
Annealed condition, per ASTM F1295 for UNS R56700.
| Condition | Property | Value |
|---|---|---|
| Annealed | Tensile strength (UTS) | ≥900 MPa (130 ksi) |
| Annealed | 0.2% yield strength | ≥800 MPa (116 ksi) |
| Annealed | Elongation at break | ≥10 % |
| Annealed | Reduction of area | ≥25 % |
| — | Elastic modulus | 105 GPa |
Confirm against the mill test report. Mechanical properties are close to those of Ti-6Al-4V, with a slightly lower elastic modulus.
| Environment | Performance | Notes |
|---|---|---|
| Body fluids / physiological | Excellent | Biocompatible; implant-grade |
| Seawater / marine | Excellent | Resists chloride attack |
| Atmospheric / general | Excellent | Titanium oxide film |
| Oxidizing acids | Excellent | Stable passive film |
| Crevice / pitting | Excellent | Highly resistant |
Corrosion resistance is characteristic of titanium — excellent in physiological and chloride media — combined with the vanadium-free chemistry and excellent biocompatibility that make it well suited to long-term implants.
An alpha-beta titanium alloy; can be used annealed or strengthened by solution treatment and ageing. Normally supplied annealed.
Solution Treatment Solution treat at approximately 900–960 °C (below the beta transus, ~1010 °C) and quench. Annealing at approximately 700–790 °C (air cool) is used for the standard annealed condition.
Ageing Age at approximately 480–600 °C to precipitate fine alpha and develop higher strength where required. Protect from oxygen, nitrogen and hydrogen pickup at temperature.
Weldable by inert-gas processes; the weld pool and cooling weld must be fully shielded from atmospheric contamination, which causes embrittlement. Post-weld stress relief or annealing is commonly applied.
| Welding Process | Applicability | Filler / Consumable |
|---|---|---|
| GTAW / TIG | Good | Matching Ti-6Al-7Nb filler |
| GMAW / MIG | Good | Matching filler |
| EBW / laser / resistance | Good | Autogenous or matching filler |
Use full inert-gas shielding and clean, contamination-free surfaces; avoid hydrogen, oxygen and nitrogen pickup. Post-weld heat treatment is common.
Machining Guidelines
| Parameter | Recommendation |
|---|---|
| Machinability | Difficult; slow speeds, heavy feeds, rigid tooling |
| Coolant | Large volume of non-chlorinated cutting fluid |
| Note | Practices similar to austenitic stainless steel |
Forming Processes
| Process | Notes |
|---|---|
| Cold forming | Difficult even when annealed; limited |
| Hot forming | ~540–760 °C (creep/hot forming); finish-forge below beta transus |
| Industry | Typical Components | Key Requirements |
|---|---|---|
| Orthopedic | Hip and knee prostheses, bone plates, screws | Biocompatibility + fatigue strength |
| Trauma / spinal | Nails, rods, spinal implants | Strength + biocompatibility |
| Dental | Dental implants and abutments | Biocompatibility |
| Surgical | Implantable load-bearing devices | Strength + corrosion resistance |
| Product Form | ASTM Standard | Notes |
|---|---|---|
| Bar and wire (implant) | ASTM F1295 | UNS R56700 |
| Sheet, strip and plate | ASTM F1295 | — |
| Forgings (implant) | ASTM F1295 | — |
| Welding wire | AWS A5.16 | Matching |
Ti-6Al-7Nb alpha-beta titanium alloy for surgical implants. UNS R56700.
| UNS | Al % | Beta Stabiliser | Type | Best Used For |
|---|---|---|---|---|
| R56700 | 5.5–6.5 | Nb 6.5–7.5 | Alpha-beta | Vanadium-free implant alloy; orthopedic and dental implants |
| R56401 | 5.5–6.5 | V 3.5–4.5 | Alpha-beta | Higher purity Ti-6Al-4V; implants (Grade 23 ELI) |
| R56400 | 5.5–6.75 | V 3.5–4.5 | Alpha-beta | Most-used alloy; high strength (Grade 5) |
| R56320 | 2.5–3.5 | V 2–3 | Near-alpha | Ti-3Al-2.5V; tubing (Grade 9) |
| R50400 | — | — | CP (unalloyed) | Workhorse commercially pure titanium (Grade 2) |




