METALS HISTORY- just for fun

Historical Methods of Steel-Making:

Bloomery : in a furnace where with slag (bloom) and iron combined to make wrought iron.

Pattern welding : forging various types of steels (wrought iron and cast iron) together for specific purposes to create swords, knives and armour for areas specific to where certain metal characteristics like strength were needed.

Catalan forge : primitive form of today’s open hearth method (see below) where pig iron’s impurities of carbon primarily are burned out.

Wootz steel : (crucible technique): developed in India by the power of windmills during tremendous winds.

Cementation process : now obsolete, used to convert bars of wrought iron into blister steel. Unlike steelmaking it increased the amount of carbon in the iron. It was apparently developed before the 17th century. The process probably originated in Bohemia in the 16th century and was in use in Bavaria in 1601.

Crucible technique :evolving after Wootz steel

Puddling : molten iron in a reverberatory furnace was stirred with rods, which were consumed in the process. Later, it was also used to produce a good-quality steel with the correct amount of carbon; this was a highly skilled art, but both high-carbon and low-carbon steels were successfully produced on a small scale, particularly for swords and other weapons.

---------------------------------------------------------------------------------------------------------

Modern methods:

Electric arc furnace : a form of secondary steelmaking from scrap, steel is hard as a resultant of this, though the process can also use direct-reduced iron. Arc furnaces range in size from small units of approximately one ton capacity used in foundries for producing cast iron products, up to about 400 ton units used for secondary steelmaking. Temperatures inside an electric arc furnace can rise to approximately 1800 degrees Celsius.
Production of Pig iron: Pig iron is raw iron, the immediate product of smelting iron ore with coke and limestone in a blast furnace. Pig iron has a very high carbon content, typically 3.5%, which makes it very brittle and not useful directly as a material except for limited applications. The traditional shape of the molds used for these ingots was a branching structure, formed in sand, with many individual ingots at right angles to a central channel or runner, bearing some similarity in appearance to a litter of piglets suckling on a sow.

Bessemer process : the first inexpensive industrial process for the mass-production of steel from molten pig iron. The key principle is removal of impurities from the iron by oxidation through air being blown through the molten iron. The oxidation also raises the temperature of the iron mass and keeps it molten.

The Siemens-Martin/open hearth furnace process : where a number of kinds of furnace where excess carbon and other impurities are burnt out of pig iron to produce steel. Since steel is difficult to manufacture due to its high melting point, normal fuels and furnaces were insufficient and the open hearth furnace was developed to overcome this difficulty. Most open hearth furnaces were closed by the early 1990s, not least because of their fuel inefficiency, being replaced by basic oxygen furnace or electric arc furnace.

Basic oxygen steelmaking : is a method of steelmaking in which carbon-rich molten iron is made into steel. The process is an improvement over the historically important Bessemer process.