Steel

Steel is a mixture of iron and carbon. The first steel was made by iron and oxygen working together in a converter designed by Henry Bessemer, this process is still used to make steel. Elements like sulfur and silica are removed through the process, but iron is left to strengthen the steel. After melting and mixing the elements, the liquid steel is cooled and hardened to be used as a material. Before using steel and bronze iron had taken its place. Steel wasn't a known well as a good material until there was a Bessemer method which made the production of steel faster and easier. This is a recyclable material that is used in many different forms of transportation, tools, architectures, and household items. There are different types of steel, and depending on the type, they are used in different places. Chromium steel is mainly used to make transportation such as cars, buses, and ships and its hard characteristic makes the object stable in dangerous situations. However, stainless steel is used to construct the buildings because it has good feature of resisting corrosion.

History
Four thousand years ago, in the beginning of the iron age, iron was proven as a metal that is harder and stronger than bronze which was used the most back then. Iron started to replace bronze in tools and weapons due to its strength. Later in 17th century iron's properties were well known but the development in Europe required more versatile metal. Later expansion of railroads used up iron and there was a major breakthrough in 1856 when Henry Bessemer found a useful way to reduce the carbon in iron using oxygen. Steel wasn't known well as a good material and the cost of production was expensive and slow. This ended when Bessemer came up with a method which is now called the Bessemer process.

Henry Bessemer designed a converter that looked like a pear in which iron and oxygen could work together. Iron was heated and melted while oxygen was blown through the molten metal. Oxygen was able to react with carbon and produce pure iron at the same time by passing through the molten metal. Carbon and silicon were able to be removed but too much of the carbon was eliminated and there was too much oxygen remaining. Bessemer studied harder to find a method that would not take out too much carbon but increase it and remove the oxygen that was not needed. British metallurgist Robert Mushet also started to test and research about speigeleisen which is an alloy of iron, carbon, and manganese. It was found that manganese is able to remove oxygen from the molten iron when it is added into the right quantities. This resolved Bessemer's problem and was made a great success but it was not the end. There was phosphorus remaining, which made steel brittle. In 1876 Welshman Thomas solved this problem by adding limestone. Limestone allowed the impurities like phosphorus to be removed. This success lead to the growth of the world steel industry within the drop of the expensive price.

Production
Steel is an alloy which mostly contains iron and little bit of carbon. The stuff that weakens steel like sulfur and silica is removed but iron is left which strengthens the steel. To start with, iron is melted and mixed with lime and coke. Two methods of primary steel making are BOS and EAF methods. While the BOS methods mix the recycled steel scrap with melted iron in a converter, EAF methods use high power electric arcs with very high temperature to melt those two metals and produce good steel. Next, the liquid from steel produced by BOS and EAF methods is treated in secondary steel making process. Elements could be added or eliminated and depending on the types of the steel needed, the processes are different. Stirring, ladle furnace, ladle injection, and degassing are the processes that could be used in secondary steel making.

After the process of melting and mixing, the molten steel is poured into a cooled mold and it cools down to become solid. When it cools down and forms a thin steel shell, the shell strand is made with guided rolls and cut into various lengths as needed. For example, it is cut into billets for products like wire and slabs for thin and flat products like plate and strip. Then it goes to a process that removes impurities and form into required shapes. This process is called hot rolling and the products that went through this process are divided into four categories: flat, long, specialty products, and seamless tube. Lastly, techniques like shaping, machining, joining, and coating determines the final shape and properties of the steel.

Uses
Steel is recyclable but the properties remain no matter how many times it is recycled. And it is not hard to produce because it does not need a large amount of energy compared to other materials. This useful material even made efforts to limit pollution and it is the world's most recycled material. There are over 3500 different types of steel with different properties. One of them is chromium steel which is mainly used to make transportation such as airplanes, cars, buses, and bicycles. This material has developed a lot compared to the past. These days cars that were built with new steel are stronger but lighter up to twenty percent. Another type of steel high carbon steel is hard and brittle, so it is used to make cutting tools and weapons. The steel without brittleness is nickel steel which is most widely used among the alloys. This type of steel is non-magnetic and has similar properties with high carbon steel.

Unlike chromium steel that is mainly used to make transportation, stainless steel is used to make household cookware, buildings, and modern arts. An example of a building made out of steel is The Chrysler Building located in New York. To make the front of the top spire upright, a lot of corrosion resistant sheet metals were used. The main example of the architecture that has the stainless steel in its construction is The Gateway Arch in St. Louis. This architecture is an essential part of Jefferson National Expansion Memorial and the walls of it are created with stainless steel skin which show radiant facade. Many things are made out of steel and we could easily see household items around us that are made with it. Steel is a good material for pots, pal resists cons, and cookwares because it resists corrosion, staining, and rust. This prevents food related illness caused by faulty cookwares. Also, steel is used by many artists like Mike Bruno who used it too as a canvas to paint. Because steel resists corrosion, it takes the advantage within the weathering properties that marble and stone do not have.

Video
Here is a video that illustrates a steel making process 9l7JqonyoKA