The strength of any material can be described by a physical parameter known as Young’s modulus of elasticity, measured in force per unit area. This parameter can be used to assess the strength of aluminum and steel tubing.
At 70 degrees Fahrenheit, Young’s modulus of elasticity for aluminum is 10 million pounds per square inch (psi). Young’s modulus of elasticity for steel, regardless of its type, is around 30 million psi. This effectively means that steel tubing is three times stronger than aluminum tubing of the same dimensions.
Size for size, steel is around three times heavier than aluminum. However, because the walls of aluminum tubing need to be three times thicker than steel tubing to achieve the bending strength, any weight advantage is lost.
The strength of aluminum or steel tubing is also dependent on the diameter of the tubing. The smaller the diameter of the tubing the more inherent strength it has and vice versa.