Tensile strength measures the maximum stress a material can withstand before breaking.
Pure titanium: Has a tensile strength of about 240–590 MPa (35,000–85,000 psi), depending on purity and processing.
Titanium alloys (e.g., Ti-6Al-4V, the most common): Exhibits much higher tensile strength, typically 860–1,100 MPa (125,000–160,000 psi) in annealed or heat-treated forms. This makes it significantly stronger than most aluminum alloys.
Pure aluminum: Has a low tensile strength of around 90–110 MPa (13,000–16,000 psi).
Aluminum alloys (e.g., 6061-T6, 7075-T6): Are stronger than pure aluminum but still generally weaker than titanium alloys. For example:
6061-T6: ~310 MPa (45,000 psi)
7075-T6 (a high-strength alloy): ~500–570 MPa (72,000–83,000 psi)
Even the strongest aluminum alloys (like 7075-T6) fall short of the strength of Ti-6Al-4V.
Yield strength is the stress at which a material begins to deform permanently.
Ti-6Al-4V: Yield strength ranges from 800–1,000 MPa (116,000–145,000 psi) in annealed or heat-treated conditions.
High-strength aluminum alloys: 7075-T6 has a yield strength of ~480 MPa (69,000 psi), while 6061-T6 is ~276 MPa (40,000 psi).
Again, titanium alloys outperform aluminum alloys in yield strength.
This is a critical metric for applications where weight is a concern (e.g., aerospace, automotive). Titanium has a density of ~4.5 g/cm³, while aluminum is lighter at ~2.7 g/cm³. However:
Ti-6Al-4V's strength-to-weight ratio is roughly 200–240 MPa·cm³/g (depending on strength).
High-strength aluminum alloys like 7075-T6 have a strength-to-weight ratio of ~185–210 MPa·cm³/g.
Thus, titanium alloys maintain a slight edge in strength-to-weight ratio, meaning they provide more strength per unit weight than even the strongest aluminum alloys.
Aluminum's strength drops significantly at temperatures above 150–200°C (300–400°F) due to softening. In contrast, titanium alloys like Ti-6Al-4V retain much of their strength at temperatures up to 400–500°C (750–930°F), making them far more suitable for high-heat applications (e.g., jet engine components).
In nearly all strength-related metrics-tensile strength, yield strength, strength-to-weight ratio, and high-temperature performance-titanium (especially its alloys like Ti-6Al-4V) is stronger than aluminum and its alloys. Aluminum's advantage lies in its lower cost and lighter weight in applications where extreme strength is not required, but for high-performance uses demanding maximum strength, titanium is superior.
