Titanium Grade 5 vs Grade 23: What's the Difference?
Jan 19, 2026
Same Base Alloy, Different Chemistry
Grade 5 (Ti-6Al-4V) and Grade 23 (Ti-6Al-4V ELI) share the same nominal composition: approximately 6% aluminum, 4% vanadium, and the balance titanium. The difference lies in the interstitial elements. Grade 23 restricts oxygen to 0.13% max, iron to 0.25% max, carbon to 0.08% max, and nitrogen to 0.05% max, while Grade 5 allows oxygen up to 0.20% and iron up to 0.40% in most product specifications. This tighter control is what makes Grade 23 "extra low interstitial" and changes its mechanical behavior.
Mechanical Property Comparison
| Property | Grade 5 (Ti-6Al-4V) | Grade 23 (Ti-6Al-4V ELI) |
|---|---|---|
| Ultimate tensile strength (annealed bar) | 895 MPa min | 860 MPa min |
| Yield strength (annealed bar) | 828 MPa min | 795 MPa min |
| Elongation in 4D | 10% min | 10% min |
| Fracture toughness (KIC) | Typically 60-80 MPa-m0.5 | Typically 80-110 MPa-m0.5 |
| Biocompatibility | Moderate | Excellent |
Values follow ASTM B348 for bar. The ELI version trades roughly 35 MPa of tensile strength for markedly better toughness and crack growth resistance.
ELI Effects: Ductility, Toughness, and Fatigue
Oxygen and nitrogen strengthen titanium by interstitial solid solution, but they also reduce ductility and fracture toughness. By lowering these elements, Grade 23 achieves higher resistance to crack initiation and propagation. In fatigue-critical parts, the improvement in crack growth threshold is often more valuable than the slight loss in static strength. This is why Grade 23 is specified for implants, cryogenic vessels, and fracture-critical aerospace components, where a failure cannot be tolerated.
Applications of Grade 5 and Grade 23
Grade 5 is the general-purpose workhorse: airframe structures, engine components, fasteners, marine hardware, and industrial equipment where maximum strength per unit weight is the priority. Grade 23 is chosen where toughness, fatigue, and biocompatibility dominate: surgical implants such as hip stems and bone plates, dental components, cryogenic tanks and piping, and aerospace parts that operate in low-temperature or high-cycle conditions.
How to Choose
Start from the service requirement. If the part carries high static loads and weight is critical, Grade 5 usually wins on strength and cost. If the part faces cyclic loading, low-temperature service, or human tissue contact, Grade 23 is the safer specification. In both cases, verify the applicable standard: ASTM B265 for sheet and plate, ASTM B348 for bar, ASTM B861 and B862 for pipe and tube, and ASTM F136 for implant material.
Frequently Asked Questions
Is Grade 23 stronger than Grade 5?
No. Grade 5 has slightly higher minimum tensile and yield strength; Grade 23 offers better ductility, fracture toughness, and fatigue resistance instead.
Can Grade 5 be used for medical implants?
Implants normally require Ti-6Al-4V ELI certified to ASTM F136; Grade 5's higher oxygen and iron limits do not meet implant specifications.
What does ELI stand for?
Extra low interstitial, meaning tighter limits on oxygen, nitrogen, carbon, and iron.
Why is Grade 23 preferred for cryogenic service?
The lower interstitial content preserves ductility and toughness at low temperature, where standard Grade 5 can become brittle.
Are Grade 5 and Grade 23 weldable?
Both are weldable with GTAW and proper shielding, but Grade 23's lower interstitials reduce the risk of weld zone embrittlement.
How do the prices compare?
Grade 23 commands a premium because of stricter chemistry control and typically lower production yields; expect a meaningful cost difference per ton.
