Titanium Alloys - Ti6Al4V Grade 5

This alpha-beta alloy is the workhorse alloy of the titanium industry. The alloy is fully heat treatable in section sizes up to 15mm and is used up to approximately 400°C (750°F). Since it is the most commonly used alloy – over 70% of all alloy grades melted are a sub-grade of Ti6Al4V, its uses span many aerospace airframes and engine component uses and also major non-aerospace applications in the marine, offshore and power generation industries in particular.

The addition of 0.05% palladium, (grade 24), 0.1% ruthenium (grade 29) and 0.05% palladium and 0.5% nickel (grade 25) significantly increase corrosion resistance in reducing acid, chloride and sour environments, raising the threshold temperature for an attack of well over 200°C (392°F).

Ti6Al4V ELI (Grade 23)

The essential difference between Ti₆Al₄V ELI (grade 23) and Ti₆Al₄V (grade 5) is the reduction of oxygen content to 0.13% (maximum) in grade 23. This confers improved ductility and fracture toughness, with some reduction in strength. Grade 23 has been widely used in fracture critical airframe structures and for offshore tubular. Mechanical properties for fracture critical applications can be enhanced through processing and heat treatment. Grade 29 also having a lowered level of oxygen will deliver similar levels of mechanical properties to grade 23 according to processing.

Composition

Table 1. The composition of Ti6Al4V Grade 5.

Key Properties

Physical Properties

Table 2. Typical physical properties for Ti6Al4V.

Mechanical Properties

Table 3. Typical mechanical properties for Ti6Al4V.

Fabrication

• Weldability – Fair
• Forging – Rough 982°C (1800°F), finish 968°C (1775°F)
• Annealing - 732°C (1350°F), 4hr, FC to 566°C (1050°F), A.C. F.C. not necessary for bars
• Solution Heat Treating – Forgings
• Aging – 904-954°C (1660-1750°F), 5 min-2hrs, W.Q. 538°C (1000°F), 4hr, A.C.

Applications

As mentioned previously, this alloy is the most popular of the titanium alloys. It is used for a range of applications in the aerospace, marine, power generation and offshore industries.