Titanium alloys are known for their excellent strength, corrosion resistance, light weight, and biocompatibility. They are widely used in the aerospace, medical, and chemical industries. Grade 5 (Ti-6Al-4V) and Grade 23 (Ti-6Al-4V ELI) are the most widely used, but they do have some small differences. In this article, we will explore the differences between these two titanium alloys and provide guides about which one to choose for your specific needs.

Grade 5 and Grade 23: Similar Chemical Composition

Both Grade 5 (Ti-6Al-4V) and Grade 23 (Ti-6Al-4V ELI) belong to the Ti-6Al-4V alloy family, which means that they are both primarily titanium (Ti) and contain approximately 6% aluminum (Al) and 4% vanadium (V). These elements give the alloy excellent overall properties:

Titanium (Ti): As a matrix, it provides good strength, corrosion resistance, and biocompatibility.

Aluminum (Al): Improves the alloy’s strength, heat, and oxidation resistance.

Vanadium (V): Improves strength, toughness, and workability of alloys.

Grade 23, also known as Ti-6Al-4V ELI (Extra Low Interstitial), is a purer version of Grade 5 with lower levels of oxygen, nitrogen, carbon, and iron. There are some small differences in the amount of impurity elements:

Element Grade 5 (wt.%) Grade 23 (wt.%)
O ≤ 0.20 ≤ 0.13
N ≤ 0.05 ≤ 0.03
C ≤ 0.08 ≤ 0.08
Fe ≤ 0.40 ≤ 0.25

Key Differences Between Grade 5 and Grade 23

The lower impurity content, especially oxygen content, gives Grade 23 better performance than Grade 5:

  • Higher fracture toughness: Grade 23 shows better resistance to crack growth at low temperatures, which means it is less prone to brittle fracture.
  • Better fatigue performance: Grade 23 exhibits longer service life under cyclic loads, which is critical for components subjected to alternating stresses.
  • Better biocompatibility: Lower impurity levels reduce the risk of adverse reactions after implantation, making Grade 23 Titanium ideal for orthopedic implants.

However, the strength of Grade 23 is slightly lower than that of Grade 5 because of the role of oxygen in solid solution strengthening in titanium alloys. These gap elements make them show differences in performance and application.

Typical Applications of Grade 5 (Ti-6Al-4V)

  • Aerospace: Used in the manufacture of aircraft engine components, turbine blades, fuselage structures and landing gear.
  • Automotive Industry: High-performance vehicle parts like suspension systems and exhaust systems.
  • Marine Applications: Propeller shafts, underwater equipment, and offshore components. Chemical: Used to manufacture corrosion-resistant chemical equipment like heat exchangers, pressure vessels, and reaction vessels. Sports Equipment: Lightweight frames, bicycle parts, and golf clubs.
  • Medical: Used in the manufacture of orthopedic implants and dental instruments.

Typical Applications of Grade 23 (Ti-6Al-4V ELI)

  • Medical: Widely used in the manufacture of long-term implants, such as artificial joints, bone fixation devices, and dental implants.
  • Dental Applications: Abutments, crowns, and orthodontic devices.
  • Surgical Instruments: Scalpels, forceps, and other high-precision tools.
  • Biomedical Devices: Pacemaker cases, defibrillator housings, and various prosthetic devices.
  • Cryogenic Applications: Components used in low-temperature environments.

The key difference is shown in the following table:

Property Grade 5 (Ti-6Al-4V) Grade 23 (Ti-6Al-4V ELI)
Composition Standard Extra Low Interstitial
Strength Higher Slightly Lower
Ductility Lower Higher
Corrosion Resistance High Slightly Higher
Applications Aerospace components, marine parts, sports equipment, and chemical processing Medical implants, surgical tools, dental implants, and cryogenic applications
Cost Generally Lower Generally Higher

Therefore, when choosing titanium alloy materials, strength and toughness need to be balanced according to your specific requirements: Grade 5 is needed for high strength, excellent corrosion resistance, or working on industrial or aerospace applications where cost efficiency is important.  However, if you need enhanced toughness and better biocompatibility and are working with medical or cryogenic applications where purity is critical, choose Grade 23.

Conclusion

Ti-6Al-4V (Grade 5) and Ti-6Al-4V ELI (Grade 23) exhibit similar chemical compositions and offer remarkable properties. However, their performance characteristics and application domains differ significantly due to variations in interstitial element content. Grade 5 is extensively utilized in the aerospace and chemical industries, owing to its superior strength and excellent corrosion resistance. In contrast, Grade 23 is predominantly favored in medical and high-end engineering applications for its outstanding biocompatibility and enhanced toughness. A comprehensive understanding of the distinctions between these two alloys facilitates the selection of the most suitable material for specific application contexts, ultimately leading to optimized product performance and extended service life.