When a part needs to be light, strong, and corrosion-resistant, engineers usually choose between aluminum and titanium alloys. Both are lighter than steel, but they differ significantly.
Density
Aluminum ~2.7 g/cm³, Titanium ~4.4 g/cm³, Steel ~7.85 g/cm³. Aluminum wins on raw weight; titanium has a higher strength-to-weight ratio.
Strength
Ti-6Al-4V (~950 MPa) is roughly 3× stronger than A6061 (~310 MPa) and retains strength at 400°C. A7075 sits in between.
Machinability
Aluminum is easy to machine and supports high speeds. Titanium has low thermal conductivity and tends to work-harden — tool life can drop to 10% of aluminum, requiring lower speeds, high-pressure coolant, and coated carbide or ceramic inserts. Cost reflects this: titanium machining is typically 3-8× more expensive than aluminum.
When to choose which
Aluminum: consumer electronics, structural parts, anodizing finishes, cost-sensitive volume production. Titanium: aerospace critical parts, medical implants, marine/chemical environments, high-temp applications.
