Grade 5 titanium alloy, universally known as Ti-6Al-4V, is the most widely utilized titanium alloy across aerospace, biomedical, marine, and industrial sectors. It is classified as an + (alpha-beta) titanium alloy, a dual-phase material that combines the high-temperature stability of the alpha phase with the ductility and forgeability of the beta phase. This classification stems from its chemical composition: approximately 6% aluminum (Al), an alpha-phase stabilizer, and 4% vanadium (V), a beta-phase stabilizer, with titanium (Ti) as the balance. The presence of both stabilizers results in a microstructure that retains a mixture of hexagonal close-packed (HCP) alpha and body-centered cubic (BCC) beta phases at room temperature, endowing the alloy with a unique balance of mechanical properties.
As an + alloy, Grade 5 exhibits exceptional versatility.
It can be heat-treated via solution treatment and aging (STA) to significantly enhance its tensile strength, reaching up to 1,100 MPa, while maintaining good ductility and fracture toughness. Unlike pure alpha alloys, which are limited in strength, or pure beta alloys, which are more difficult to process, Grade 5 strikes an optimal balance, making it suitable for critical components requiring high strength-to-weight ratios, fatigue resistance, and corrosion resistance. It is also highly weldable and can be fabricated into various forms, including sheets, bars, forgings, and additive manufacturing parts, further solidifying its status as the "workhorse" of titanium alloys.
Regarding its physical properties, the density of Grade 5 titanium alloy is approximately 4.42 g/cm³ (or 4420 kg/m³) at room temperature.
This density is notably lower than that of steel (approximately 7.85 g/cm³) and nickel-based superalloys, yet it delivers comparable or superior strength in many applications. This low density, paired with its high strength, gives Grade 5 an outstanding strength-to-weight ratio-approximately 40% lighter than steel with equivalent mechanical performance. This characteristic is pivotal in aerospace engineering, where weight reduction directly translates to fuel efficiency and increased payload capacity, and in biomedical implants, where lightweight materials reduce patient discomfort and improve biocompatibility.
The density of Grade 5 remains relatively stable across typical operating temperatures, from cryogenic conditions up to approximately 427℃ (800℃F), the upper limit for its reliable use. Minor variations in density can occur due to slight differences in chemical composition (e.g., trace elements like oxygen, iron, or carbon) or manufacturing processes, but these deviations are negligible for most industrial applications. Standard specifications such as ASTM B265 and AMS 4911 define the acceptable composition ranges and physical property tolerances for Grade 5, ensuring consistency in its density and performance.
Grade 5 (Ti-6Al-4V) is a dual-phase + titanium alloy celebrated for its balanced mechanical properties and processability. With a density of 4.42 g/cm³, it offers an unparalleled strength-to-weight ratio, making it indispensable in high-performance industries where lightweight, strength, and durability are non-negotiable.
