ABOUT STEEL


History of Steel Making Processes

At 1850's molten iron was refined to first produce wrought iron, which was nearly impurities free ferrous material containing small amount of mechanically entrapped slag practice. This was known as a "blisters" or "cement" steel and the process is called cementation process steel making.

Then in 1740 Huntsman, in U.K who successfully melted the cement steel in a crucible and thereby laid the foundation of crucible steel making process. After some years in 1860's "Henry Bessemer" perfected his process of steel making in U.K through the blowing of cold air to molten iron and producing steel in molten condition first time.

After Henry, Thomas from Germany in 1878 modified the Bessemer process and made it applicable to irons containing phosphorus and sulphur, and developed the Basic Bessemer which also known as Thomas Process.

In year of 1868 William and Fredrick in Germany and Emile and Pierre Martin in France developed a furnace using the heat generation principle to raise the furnace temperature up to 1600℃, By which it melt steel scrap also refining the melt and produce molten steel. This process is known as "Siemens-Martin" or Open heart process. The basic open hearth process dominated the steel production for almost one hundred years and then is being replaced by the more faster economical and easily controllable oxygen steelmaking processes.

By the turn of previous century Paul Heroult successfully put the "electric arc furnace" in to practice for making steel by melting steel scrap. Ferranti concurrently developed the "induction furnace" for melting scrap. Both are still consider to be the best alternative for conversation of steel scrap to steel.

The possibility of producing cheap oxyegn by the Linder Frankly process on tonnage scale finally led to the development of LD, Kaldo and the Rotor process of steelmaking using pure oxygen as refining agent on commercial level by 1950's. This is the beginning of modern steel oxygen steelmaking or more popularly as basic oxygen furnace BOF for short, processes of steelmaking.

Then Bessemer, open hearth and electric furnace to modify themselves by using oxygen as far as possible in refining and also in melting. This led to the development of a series of modified conventional processes like Ajax, SIP, Tandem, Twin-hearth etc. The material engineering developed to the extent that it has now become possible to blow oxygen form bottom. This is known as Q-BOP or OBM process of steelmaking.

Similarly LD-AC was developed to blow lime powder along with pure oxygen to tackle the thomas grade iron and produce good quality steel. The lastest in the field is some form of combination of bottom gas blowing and top blowing of oxygen in the form of modified LD process now known as bath agitated process, BPA for short or combined blowing processes of steel making. To meet more and more stringent demand on the steel quality a series of secondary steel making technique have lately been developed and put in to practice. These fall in category of Ladle Metallurgy or decarburization or remelting technique, roundish metallurgy and so on. These is carried out with or without vaccum.


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