Comparison Between Medical Titanium Rods: Gr5 and Gr23
Introduction
In medical titanium alloys, both Gr5 and Gr23 are Ti-6Al-4V series alloys with key differences in composition, mechanical properties, and applications. These distinctions make them suitable for different medical applications. Below is an in-depth comparison of Gr5 and Gr23 in terms of alloy composition, mechanical properties, biocompatibility, and typical uses.
1. Alloy Composition and Impurity Control
Gr5 (Ti-6Al-4V): Contains approximately 6% aluminum and 4% vanadium, with a relatively higher oxygen content.
Gr23 (Ti-6Al-4V ELI): Known as the 'Extra Low Interstitial' version, Gr23 has reduced levels of impurities, especially oxygen, providing a higher purity and improved biocompatibility.
Element | Gr5 (Ti-6Al-4V) | Gr23 (Ti-6Al-4V ELI) |
Aluminum (Al) | 5.5-6.75 per cent | 5.5-6.5 per cent |
Vanadium (V) | 3.5-4.5 per cent | 3.5-4.5 per cent |
Oxygen (O) | ≤ 0.20% | ≤ 0.13% |
Nitrogen (N) | ≤ 0.05% | ≤ 0.03% |
Carbon (C) | ≤ 0.08% | ≤ 0.08% |
Hydrogen (H) | ≤ 0.015% | ≤ 0.012% |
2. Mechanical Properties
Gr5 has slightly higher strength, making it suitable for high-strength applications. Gr23, with reduced oxygen and other impurities, offers improved ductility and toughness, especially beneficial in dynamic environments.
Property | Gr5 (Ti-6Al-4V) | Gr23 (Ti-6Al-4V ELI) |
Tensile Strength | 895-930 MPa | 860-895 MPa |
Yield Strength | 830-880 MPa | 795-830 MPa |
Elongation | 10-15% | 15-18% |
Reduction in Area | ≥ 25% | ≥ 30% |
Hardness (HRC) | 32-36 | 28-33 |
3. Biocompatibility and Applications
Gr5: Due to its higher oxygen content, Gr5 has slightly lower biocompatibility compared to Gr23. It is generally used for medical tools (such as surgical instruments) and dental implants where short-term use or high strength is prioritized.
Gr23: With a lower level of impurities, Gr23 provides superior biocompatibility, making it ideal for long-term implants such as hip joints, knee joints, bone plates, and screws.
Category | Gr5 Applications | Gr23 Applications |
Primary Use | Surgical tools, dental implants | Long-term implants: hip joints, bone screws |
Corrosion Resistance | Good in body fluids | Superior in long-term body exposure |
High Strength Application | High strength for short-term implants | Durability in dynamic joint environments |
Conclusion
The main differences between Gr5 and Gr23 titanium alloys lie in the levels of impurities and resulting mechanical properties. Gr5 is more suited for applications requiring high strength, like medical instruments, whereas Gr23's higher biocompatibility and toughness make it ideal for long-term implants in the human body.
