Steel: Steel contains iron with a small percentage of carbon added it. Iron itself is not very strong but the additions of small percentage of carbon in it decrease the ductility of steel. Therefore, if the carbon content is too high the steel is brittle. On the basis of the percentage of carbon in steel, it can be classified as:
1. Mild steel contains 0.25% carbon.
2. Medium steel contains 0.45% carbon.
3. High carbon steel contains carbon about 0.70% or above.
Properties:
1. Its resistivity varies from 10*10-8 or 14*10-8 ohm-m.
2. It has better mechanical properties.
3. It is ductile but ductility with increase in carbon content in it.
4. It is easily corroded when exposed to moisture and a zinc coating is provided on its surface to make it corrosion resistant.
Uses: Aluminium conductors are steel reinforced to increase their tensile strength for use as overhead transmission line conductors. Galvanised steel are wires are used as overhead telephone wires an earth wires.