According to a theory of classical archeology, the processing of iron ore for the first time in the world occurred as a result of the great forest fire that broke out in the Kaz Mountains in Turkey in ancient times, as a result of the heating of the soil to such an extent that the iron contained in it could be shaped. Another theory is that humans learned to process iron thanks to meteorites falling to earth. It is accepted that humans were able to make primitive tools and weapons, most likely by forging and processing metal from meteorites.

Although iron and steel have been used for 5000 years, they were only involved in the making of weapons and goods until two centuries ago. However, with the beginning of raw iron production in England in the 18th century, iron began to be used as a building material.

The first structures built using iron were bridges. The first material used is the font. Font has high compressive strength and low tensile strength.

The first bridge built using the font was the Coalbrookdale Bridge over the River Severn in England, estimated to have been completed around 1778. It was built by Abraham Darby. Abraham Darby was the first person to be able to produce coke using hard coal and to process iron using coke. Until the 1700s, charcoal was used to process iron because of its rich carbon content, but deforestation in Europe in those years made iron processing difficult. There was plenty of hard coal in England, but not enough carbon in hard coal. It is considered an invention.)

In the following years, with the discovery of Bessemer (1855), Siemens-Martin (1864), Thomas (1879) methods, the purification of raw iron in liquid state has been achieved and the possibility of cast steel production has emerged. Thus, since the late 1800s, cast steel has been the most produced type. Especially at the beginning of the 20th century, with the use of electric furnaces, great progress has been made in steel construction techniques.

Due to the rapid construction of steel structures, steel structure construction was widely observed after the first world war, during and after the second world war. Steel construction was preferred in order to re-produce the industry, which was disintegrated after the First World War. During the Second World War, the German army occupied the lands of dozens of states up to the Volga River, dismantled the equipment of the industrial buildings, moved them to new lands, and started rapid industrial production in these lands, only with the use of steel carrier systems.

After the war, the need for rapid construction of industry, social-sports facilities, school and residential buildings was only possible with the use of steel. Thus, it has been possible to develop the calculation methods and design principles of steel structure carrier systems. In this process, welding techniques have also developed.

Iron is the most abundant metal in the earth's crust and constitutes approximately 4.5% of the crust. It is not found as a free element, except in meteorites. Iron ore in nature;

– Oxides [magnetite (Fe3O4) and hematite (Fe2O3)],

– Hydroxides [geotite (FeO(OH)) and limonite (FeO(OH)·nH2O)],
– Carbonates [siderite(Fe2CO3)]

(Figure 1). Almost all ore types contain Silicon Oxide (Si2O). Most ore types contain small amounts of Phosphorus, Aluminum, Sulfur, etc. contains elements.

1. a) magnetite
   b) Hematite
   c) Geotite
   d) Limonite
   e) Siderite

Iron ore is burned with coke in a blast furnace and melted to obtain raw iron. Coke has two functions; the first is to provide the required temperature, and the second is to enter into a chemical reaction with the iron. The carbon in the coke forms an alloy with the iron, and this alloy also contains substances such as Silicon, Aluminum, Sulfur, which comes from the raw iron ore. Slag and blast furnace gases are also produced at the end of the process. Since the slag is low in density, it collects on the molten raw iron and is thrown out of the slag hole in the blast furnace. Since the carbon ratio of the obtained raw iron is high (3-5%), it is not suitable for deformation and weldability. For these reasons, steel or cast iron can be produced by processing raw iron, depending on the method and additives used. It is produced in a cast iron cupola furnace. It contains approximately 2~4% carbon. Steel, on the other hand, can be obtained by methods such as Siemens-Martin, Electric Arc, Oxygen Blowing. As a result of these methods, cast steel, forged steel or rolled steel is obtained.