PIg iron was widely produced during the Industrial Revolution.
Pig iron is a byproduct of the smelting process to make pure iron. The iron ore is heated using high carbon fuel coke, which results in pig iron with a very high carbon content, usually around 4 percent. During the Industrial Revolution, pig iron was widely used. Pig iron is now normally forged into wrought iron, which is a more useful material. It does have some useful properties, but because of modern metallurgical methods, better materials are now available.
Chemical Composition
All forms of pig iron contain between 3.5 and 4.5 percent carbon, along with various amounts of silicon, manganese, sulphur and phosphorous. Basic pig iron has less than 1.5 percent silicon, under 1 percent manganese, and trace amounts of sulphur and phosphorous. Haematite pig iron has similar amounts of these impurities, but a much higher silicon content, normally between 1.5 and 3.5 percent. The most common form of this materail, nodular pig iron, has no silicon and 0.05 percent manganese, sulphur and phosphorous.
Brittleness
Pig iron is a very brittle metal, owing to the high carbon content and the other impurities that form in it. The other elements found in pig iron also weaken its structure. Although iron is thought of as very solid, pig iron will split and fracture if it is dropped.
Melting Point
Pig iron has a much lower melting point than wrought iron or steel due to the high carbon content. This is not a problem in terms of the physical properties, but it does allow it to be made into low-grade grey iron, a mix of pig iron and scrap steel and iron.
Graphite
The impurities in pig iron lead to other materials forming during the cooling process. The iron and carbon combine to make iron carbide, and the remaining carbon forms graphite, similar to that found in pencils. If the pig iron is allowed to cool too slowly, larger amounts of graphite form, weakening the material.
Applications
Most of the pig iron produced as of 2011 is not used in the same way as it once was. It is usually forged to create wrought iron, or its carbon content is reduced to form steel. During the Industrial Revolution, before advanced forging techniques were discovered, pig iron was used for any number of molded iron products.
Tags: carbon content, high carbon, high carbon content, Industrial Revolution, sulphur phosphorous, wrought iron, between percent
