An Iron Glossary
Cast Iron: Cast iron is strong but can be brittle due to its carbon content, making it less than ideal for working and shaping. As metallurgists became aware that the high carbon content in iron was central to the problem of brittleness, they experimented with new methods for reducing the carbon content in order to make iron more workable.
Pig Iron: Molten iron that was run out of the furnaces and cooled in a main channel and adjoining molds became referred to as pig iron because the large, central and adjoining smaller ingots resembled a sow and suckling piglets.
Wrought Iron: By the late 18th century, ironmakers learned how to transform cast pig iron into a low-carbon content wrought iron using puddling furnaces (developed by Henry Cort in 1784). The furnaces heated molten iron, which had to be stirred by skilled puddlers using long oar-shaped tools, allowing oxygen to combine with and slowly remove carbon. As the carbon content decreases, iron’s melting point increases, so masses of iron would agglomerate in the furnace. These masses would be removed and worked with a forge hammer by the puddler before being rolled into sheets or rails.