Steel

Steel is a alloy made of Iron and Carbon (0.5%-1.5%) and is widely used in the construction and infrastructure because of its high tensile strength and inexpensive cost. Tensile strength measures the breaking point of a material while being pulled or stretched. Steel mills add carbon to the iron to make it stronger; this occurs because the iron molecules can not move around as much when force is applied because it is locked together by carbon atoms. Steel used to be made in bloomery furnaces for thousands of years, however the process was not efficient and until the 19 century steel was mass produced because of the Bessemer furnace. However, currently Bessemer method is not used to commercial manufacture steel because the new method that is used makes it 10 times faster than the Bessemer method.

The current method used in manufacturing steel uses a basic oxygen furnace to create steel. First, high purity oxygen blows through the molten pig iron, lowering the amount of  silicon and magnesium compounds. Then they add cleaning agents called fluxes to reduce the sulfur and phosphorus levels.