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Introduction

Grade 23 titanium, commonly known as Ti-6Al-4V ELI, is an extra-low-interstitial version of the widely used Grade 5 titanium alloy.

Both grades contain aluminum and vanadium as their principal alloying elements. The main distinction is that Grade 23 has more restrictive limits for certain interstitial elements, particularly oxygen and iron-related impurity controls under the relevant specifications.

These controls are important because interstitial elements can influence ductility, fracture toughness, and other mechanical characteristics.

Grade 23 is widely associated with biomedical and surgical implant applications. It is also used in selected aerospace, marine, cryogenic, and high-performance engineering applications.

However, the designation Grade 23 alone does not automatically mean that a material or finished medical device is certified for a particular implant application. The governing specification, material condition, processing history, documentation, and applicable regulatory requirements must all be considered.

1. What Is Grade 23 Titanium?

Grade 23 is an alpha-beta titanium alloy based on Ti-6Al-4V chemistry.

Its common designations include:

The difference in UNS designations is specification-dependent. Do not assume that one UNS number applies universally to Grade 23 under every standard.

Grade 23 is not a commercially pure titanium grade. It is a modified version of the Ti-6Al-4V alloy family with tighter interstitial-element controls.

2. What Does ELI Mean?

ELI stands for Extra Low Interstitials.

Interstitial elements are atoms that occupy spaces within the titanium crystal structure. Oxygen, nitrogen, carbon, and hydrogen can influence titanium's mechanical behavior.

In Ti-6Al-4V ELI, the relevant limits are controlled more tightly than in standard Grade 5 under the applicable specifications.

The purpose is to achieve a material property balance suitable for applications where ductility and fracture toughness are important.

ELI does not mean that the material contains no interstitial elements. It means that the specified limits for selected elements are lower.

3. Chemical Composition

Grade 23 retains the basic Ti-6Al-4V alloy system.

A commonly referenced composition range for Ti-6Al-4V ELI includes:

| Element | Commonly Referenced Requirement | |---|---:| | Aluminum | 5.50–6.50% | | Vanadium | 3.50–4.50% | | Iron | Maximum 0.25% | | Oxygen | Maximum 0.13% | | Carbon | Maximum 0.08% | | Nitrogen | Maximum 0.05% | | Hydrogen | Specification-dependent limit | | Titanium | Balance |

The table is for general orientation only. Exact limits and additional requirements must be checked against the applicable edition of ASTM B265, ASTM B348, ASTM F136, or another specified standard.

Different product forms and standards may have different requirements. A chemical composition table from one specification should not automatically be applied to another.

4. Mechanical Properties

Grade 23 offers a useful combination of strength and ductility.

Its mechanical properties depend on:

For this reason, generic tensile values should not be treated as guaranteed properties for every Grade 23 product.

When purchasing Grade 23 material, the required tensile strength, yield strength, elongation, and other acceptance criteria should be stated in the purchase specification.

The material test certificate should identify the applicable standard, grade, condition, heat or lot traceability, and test results required by the order.

5. Grade 23 vs Grade 5 Titanium

Grade 23 and Grade 5 share the Ti-6Al-4V alloy family, but their interstitial-element requirements differ.

| Comparison | Grade 5 | Grade 23 | |---|---|---| | Alloy family | Ti-6Al-4V | Ti-6Al-4V ELI | | Main alloying elements | Aluminum and vanadium | Aluminum and vanadium | | Interstitial control | Standard alloy requirements | Extra-low-interstitial requirements | | Ductility and fracture toughness | Depends on condition | ELI chemistry is intended to improve the relevant property balance | | Common applications | Aerospace and industrial engineering | Medical, aerospace, cryogenic, and selected marine applications | | Material selection | General high-strength applications | Applications requiring ELI material characteristics |

Grade 23 should not be described as simply a stronger or weaker version of Grade 5. The main distinction is the more restrictive interstitial-element control and the resulting property balance.

Substitution between Grade 5 and Grade 23 requires engineering approval and confirmation that the material meets the governing specification.

6. Medical and Biomedical Applications

Grade 23 is widely used in biomedical material supply chains because of its combination of mechanical properties and corrosion resistance.

Potential applications include:

The material's suitability for a medical application depends on more than its grade designation.

Relevant considerations may include:

ASTM F136 covers wrought annealed Ti-6Al-4V ELI alloy for surgical implant applications. Compliance with this material specification is not the same as certification or regulatory approval of a finished medical device.

A supplier should not claim that a finished implant is approved merely because the starting material is Grade 23.

7. Other Applications

Aerospace Engineering

Grade 23 may be considered for selected aerospace components where its material characteristics meet the engineering requirements.

Actual aerospace supply requires the applicable aerospace specification, processing controls, and documentation.

Cryogenic Applications

Grade 23 is used in selected cryogenic applications because of its material characteristics at low temperatures.

The suitability of a particular product must be confirmed for the actual temperature range, loading condition, product form, and design requirements.

Marine and Offshore Engineering

Grade 23 may be used for selected marine components. Material selection must consider the actual seawater environment, loading, fabrication, and corrosion-control requirements.

Precision Engineering

Grade 23 can also be supplied in product forms used for machining and precision manufacturing, subject to material availability and specification requirements.

8. Product Forms and Applicable Standards

Grade 23 may be supplied in different product forms, depending on the applicable specification and manufacturing route.

Common product forms include:

Examples of relevant ASTM standards include:

| Standard | General Scope | |---|---| | ASTM B265 | Titanium and titanium alloy strip, sheet, and plate | | ASTM B348 | Titanium and titanium alloy bars and billets | | ASTM B381 | Titanium and titanium alloy forgings | | ASTM F136 | Wrought Ti-6Al-4V ELI alloy for surgical implant applications |

The exact grade, product form, condition, and acceptance requirements must be checked in the current edition of the relevant standard.

ASTM F136 should not be used as a universal specification for every Grade 23 product form or every finished medical component.

9. Purchasing Grade 23 Titanium: What Should Buyers Confirm?

A clear purchase specification helps prevent misunderstandings between the buyer, material supplier, processor, and end user.

Before requesting a quotation, confirm:

  1. Grade and alloy designation.
  2. Applicable material standard and edition.
  3. Product form and dimensions.
  4. Required delivery condition.
  5. Chemical composition requirements.
  6. Mechanical-property requirements.
  7. Required testing and inspection.
  8. Material traceability requirements.
  9. Required certificates and supporting documents.
  10. Any additional customer or regulatory requirements.

For medical-related supply chains, the buyer should clearly identify whether the requirement is for raw material, semi-finished material, a machined component, or a finished device component.

These are different supply scopes and may require different quality and regulatory controls.

10. Frequently Asked Questions

Is Grade 23 the same as Ti-6Al-4V ELI?

Grade 23 is the common ASTM grade designation associated with Ti-6Al-4V ELI. The exact specification and product form should still be confirmed.

What is the difference between Grade 5 and Grade 23?

Both belong to the Ti-6Al-4V alloy family. Grade 23 has extra-low-interstitial requirements, which are intended to improve the balance of ductility and fracture toughness.

Is Grade 23 titanium used for medical implants?

Yes. It is widely used in medical material supply chains. ASTM F136 specifies wrought annealed Ti-6Al-4V ELI alloy for surgical implant applications.

Does Grade 23 automatically comply with ASTM F136?

No. The Grade 23 designation alone is not sufficient. The material must meet the applicable ASTM F136 requirements, including chemistry, mechanical properties, condition, and other specified criteria.

Are Grade 23 and Grade 5 interchangeable?

Not automatically. Substitution must be evaluated against the design requirements and governing material specification and approved by the responsible engineering or purchasing authority.

What is the difference between UNS R56407 and R56401?

ASTM B265 identifies Grade 23 as UNS R56407. ASTM F136 identifies the wrought Ti-6Al-4V ELI implant alloy using UNS R56401. The designation must be interpreted in the context of the specific standard.

Conclusion

Grade 23 titanium is an extra-low-interstitial version of Ti-6Al-4V developed for applications where its material characteristics, including ductility and fracture toughness, are important.

It is widely used in biomedical material supply chains and selected aerospace, cryogenic, and marine applications.

For procurement, buyers should confirm the exact material specification, product form, condition, testing requirements, and documentation. Grade designation alone does not establish compliance with every medical or industrial requirement.

Discuss Your Grade 23 Titanium Requirements

Feinuotai supplies titanium materials and coordinates processing solutions for industrial requirements.

For Grade 23 inquiries, please specify the required product form, dimensions, quantity, applicable ASTM or other material standard, delivery condition, and documentation requirements.

For medical-related material inquiries, please identify the exact material specification and intended supply scope so that the requirements can be reviewed accurately.

Contact our team to discuss your titanium material requirements.

References

  1. ASTM International, ASTM B265 – Standard Specification for Titanium and Titanium Alloy Strip, Sheet, and Plate.

https://store.astm.org/standards/b265

  1. ASTM International, ASTM B348 – Standard Specification for Titanium and Titanium Alloy Bars and Billets.

https://store.astm.org/standards/b348

  1. ATI Materials, ATI Ti-6Al-4V ELI Grade 23 Technical Data Sheet.

https://www.atimaterials.com/Products/Documents/datasheets/titanium/alloyed/ati_6-4eli_tds_en_v1.pdf

  1. Fort Wayne Metals, Ti-6Al-4V ELI Alloyed Titanium.

https://fwmetals.com/what-we-do/materials/titanium/ti-6al-4v-eli-alloyed-titanium

  1. ASTM International, ASTM F136 – Standard Specification for Wrought Titanium-6Aluminum-4Vanadium ELI Alloy for Surgical Implant Applications.

https://store.astm.org/standards/f136