The Difference Between Gr5 Titanium Alloy and Gr5ELI Titanium Alloy

Gr5 Titanium Alloy

Gr5 Titanium Alloy, developed in the United States in 1954, is an α-β type titanium alloy containing 6% α-stabilizing element aluminum and 4% β-stabilizing element vanadium. The nominal composition of the alloy is characterized by an aluminum equivalent of 7.0 and a molybdenum equivalent of 2.9. In its annealed state, it contains 10-15% β phase. Aluminum strengthens the α phase by solid solution strengthening, thereby enhancing the alloy's room temperature and high-temperature strength. Vanadium is one of the few alloying elements in titanium that can improve both strength and plasticity. Unlike most alloying elements, vanadium reduces the c/a axis ratio of the α phase lattice, thus improving the formation of the α phase and preventing embrittlement during long-term use.

Main Characteristics:

• Excellent comprehensive performance and good processability.
• Moderate room temperature and high-temperature strength.
• Good creep resistance and thermal stability.
• High fatigue resistance and crack propagation resistance in seawater.
• Satisfactory fracture toughness and resistance to hot salt stress corrosion.
• Less sensitivity to hydrogen compared to Gr2 and Gr1 alloys.

Gr5 Titanium Alloy is suitable for manufacturing parts operating within a wide temperature range (-196°C to 450°C), especially for components designed under damage tolerance principles. It has excellent process plasticity and superplasticity, making it suitable for various pressure forming methods, welding, and machining.

Main Forms:

• Bars, forgings, thin plates, thick plates, profiles, and wires.
• Also used for castings.
  

Gr5ELI Titanium Alloy

Gr5ELI is an improved version of Gr5, primarily distinguished by its different aluminum content and lower levels of interstitial elements such as Fe, N, H, and O.

Advantages:

• Good biocompatibility.
• Low elastic modulus and density.
• Excellent corrosion resistance.
• Non-toxic, high yield strength, and long fatigue life.
• Greater plasticity at room temperature, making it easy to form.

Gr5ELI Titanium Alloy is an ideal material for medical implants, such as cranioplasty and bone fixation, due to its enhanced strength, fatigue life, and plasticity.

Titanium Alloys:

• Titanium alloys are composed mainly of titanium with additional elements. Titanium has two allotropic forms: α-titanium (hexagonal close-packed structure below 882°C) and β-titanium (body-centered cubic structure above 882°C). By adding suitable alloying elements, the phase transformation temperature and composition content can be adjusted to obtain different titanium alloy structures.

Gr5ELI Alloy Features:

• Lower impurity elements such as Fe, which reduces strength but significantly improves ductility and toughness.
• Better plasticity, toughness, welding performance, and low-temperature performance.
• Widely used in cryogenic engineering, medical applications, naval vessels, and aircraft.

Usage Environments:

• Gr5 Alloy can be used in ordinary or high-temperature environments.
• Gr5ELI Alloy is suitable for ultra-low temperature environments.

Related Grades:

• T-6A-4V/Grade 5 (USA), BT 6 (Russia), IMI 318 (UK), TiAl6V4 (Germany).

Medical Applications:

• Used in artificial joints, bone plates, screws, hip joints (including femoral heads), knee joints, elbow joints, finger joints, mandibular bones, artificial vertebrae (spinal orthotics), pacemaker housings, artificial hearts (heart valves), dental implants, titanium orthodontic devices, and cranial prosthetics.

Attributes:

• High strength-to-weight ratio, good biocompatibility, and excellent corrosion resistance in body fluids.
• Ti 6Al-4V ELI is preferred in medical implants due to its maximum toughness, making it suitable for seawater and low-temperature environments. Typically used in the annealed state.

Production Process:

• Stress relief annealing at 900-120°F for 1-4 hours followed by air cooling.
• Double annealing for bars and forgings: solution annealing below beta transition temperature, maintaining for at least 1 hour followed by air cooling, then reheating at 1300-1400°F, maintaining for at least 1 hour followed by air cooling. Stress relief annealing is suitable post-welding.