Density of Steel
Table of Contents
What is the density of Steel?
The density of steel ranges between 7850 kg/m3 to 8050 kg/m3 (484 and 503 Ib/ft3) and this depends on its alloying constituents.
The steel density and unit weight in accordance to Eurocodes is taken between 77.0 kN/m3 and 78.5 kN/m3 (which is a density of 7700 kg/m3 and 7850 kg/m3).
The density (specific mass) of a substance is its mass per unit volume. Metal and Alloy densities vary significantly and it depends on the metal element.
To convert between kg/m3 and Ib/ft3, then we need to multiply by 0.062428. Therefore, 1 kg/m3 equals 0.062428 Ib/ft3
To convert between Ib/ft3 and kg/m3,then we need to multiply by 16. Therefore, 1 Ib/ft3 equals 16 kg/m3
The equation for density is defined below:
\(\rho = m/V\)
where
\(\rho\) = density, units are in \(kg/m^3, or Ib/ft^3, or g/cm^3\)
\(m\) = mass, units are in \(kg, or Ib, or g)\)
\(V\) = Volume, units are in \(m^3, or ft^3, or cm^3\)
How to calculate the density of Steel?
When you have an unusual shape of the steel or any other metal, you may initally wonder “what is the density of steel?”, but the density will remain constant, and it is the measured volume and mass (kg or Ib) that will change. However, the steel density depends on the method of manufacture.
When a piece of metal or steel is molded or formed in an unusual shape, the volume can be calculated using the displacement method, and the subsequent density of the metal can be calculated.
The displacement method involves the use of an electronic balance/measuring scale and a glass measuring cylinder filled with water.
The metal cube/ is placed in the cylinder filled with water. The volume displaced is equal to the amount of water displaced (measure the volume of water initially, and then after the metal has placed into the cylinder).
The mass of the metal needs to be measured beforehand using the electronic balance.
Now we have the mass of the cube and volume of the metal cube, we can calculate the density using the formula above. \(\rho = m/V\)
Steps
- Fill measuring cylinder with water and write down the volume by checking the value at the bottom of the meniscus of water (Meniscus is the curved surface of the liquid).
- Place metal cube in measuring cylinder and watch the water level rise. Measure the new volume of the water.
- The volume of the metal cube = final volume – initial volume.
- The mass can be recorded by placing metal cube on electronic balance.
- Calculate density using formula above. This is an easy method to calculate the steel density or any other materials
Example 1: Calculate weight of steel block
Determine the weight of a steel section that is 2m x 0.2m x 1m. Take the density of steel as 8050 kg/m3 .
(Note – always remember to look the units of steel density when carrying out calculations)
Total volume of block is 2 x 0.2 x 1.0 = 0.4 m3.
Total weight = density x volume
Total weight = 8050 x 0.4 = 3220 kg
