Density of aluminum alloys is
about 0.1 lb/in3 [2,700 kg/m3]
on average and doesn’t vary much because alloying elements constitute
a small portion of the composition. Since density is the weighted average of
the densities of the elements that constitute the alloy, the 5xxx and 6xxx series
aluminum alloys are the lightest because magnesium is the lightest of the main alloying
elements. The actual density of wrought aluminum alloys is usually close to the nominal
value, but the density of aluminum castings is about 95% to 100% of the theoretical
density value due to porosity.
Aluminum and aluminum alloys are characterized by a relatively low density
compared to steel.