Industrial steel is a metal alloy made of iron. It is used in the construction of buildings, bridges and other structures that require a strong, resilient material. Iron is mined from the ground in the form of iron ore and is combined with carbon to form industrial steel. Although there are several metals that can be combined with iron to form strong metal alloys, carbon is used because it is readily available and the most cost-effective of all the possible metals.
Iron ore is found in the top layer of the earth's crust. It is removed by large mining operations, which dig the iron ore out of the ground and then transport it to steel processing plants. Iron ore is converted into industrial steel through a multi-step process that is completed inside steel manufacturing plants.
The first stage in the steel making process is the extraction of excess carbon from the iron ore. There must be a specific ratio of carbon to iron before the material can progress to the next stage. The iron ore is put into a blast furnace, which is designed to create and maintain a great deal of heat for an extended period. This type of furnace is specifically designed to pump in pure oxygen, which allows the furnace to generate and maintain the high level of heat required to create industrial steel.
This high heat level is required to melt the iron ore into liquid form. The oxygen molecules from the iron ore are removed by combining the iron with carbon and forcing the oxygen bond to break. This combined iron and carbon material is subjected to multiple stages of high heat and rapid cooling, using large amounts of water in a process called smelting. During smelting, there are multiple temperature changes and the amount of carbon mixed into the steel is carefully monitored and adjusted. Adding the carbon at the wrong point, cooling too quickly or too slowly all have an impact on the quality of the steel produced.
During the final cooling stage, the iron ore and carbon mixture changes into a substance called martensite. This material is a very hard form of steel crystalline and it is created through a change in cell structure caused by the process of smelting. Testing the chemical structure of the steel is part of the quality control process used within steel manufacturing plants. In order to meet the scientific criteria for steel, the material must have a chemical structure with a 0.4 weight percentage of carbon.