Titanium Grade 23 is the Extra Low Interstitial (ELI) version of Ti-6Al-4V.
It retains the high strength, low density and corrosion resistance of the Ti-6Al-4V alloy family while applying tighter limits to oxygen, nitrogen, hydrogen and other controlled elements.
These tighter chemistry limits improve ductility and fracture-toughness characteristics, making Grade 23 particularly important for fracture-critical aerospace components and medical applications.
Grade 23 is designated UNS R56407.
Grade 23 Chemical Composition
| Element | Weight % |
|---|---|
| Titanium (Ti) | Balance |
| Aluminium (Al) | 5.5–6.5 |
| Vanadium (V) | 3.5–4.5 |
| Iron (Fe) | ≤ 0.25 |
| Oxygen (O) | ≤ 0.13 |
| Carbon (C) | ≤ 0.08 |
| Nitrogen (N) | ≤ 0.03 |
| Hydrogen (H) | ≤ 0.0125 |
Although iron is tightly controlled, it should not be described as an interstitial element. Oxygen, nitrogen, carbon and hydrogen are interstitial elements in titanium; iron is a substitutional residual element.
Grade 23 Mechanical Properties
Representative minimum annealed properties include:
| Property | Value |
|---|---|
| Ultimate tensile strength | ≥ 828 MPa |
| 0.2% yield strength | ≥ 759 MPa |
| Elongation | ≥ 10% |
| Density | approximately 4.43 g/cm³ |
Grade 23 vs Grade 5
Grade 23 and Grade 5 are both based on Ti-6Al-4V.
The primary distinction is Grade 23’s tighter control of interstitial elements, particularly oxygen. This generally improves ductility and fracture toughness, with somewhat lower specified strength than some Grade 5 product forms.
Typical Applications
- Orthopaedic implants
- Bone screws and fixation devices
- Spinal components
- Medical instruments
- Dental applications
- Fracture-critical aerospace components
- High-performance engineering components requiring ELI chemistry
Material intended for implantation must meet the applicable medical-device material specification and regulatory requirements; being called “Grade 23” alone does not establish that a particular batch is approved for a specific implant application.
Common Specifications
- ASTM F136
- ASTM B265
- AMS 4907 — ELI sheet, strip and plate
- AMS 4930 — ELI bars, wire, forgings and rings
Technical Note
Chemical and mechanical properties shown are representative of commonly referenced specifications. Requirements can vary by product form, thickness, heat treatment and governing standard. Material should be ordered to the required specification, and the supplied material test report (MTR) should be used to verify compliance.
