Pub. 5 2015 Issue 1

8 AT THE CENTER OF UTAH INDUSTRY A Primer on Iron and Iron Alloys I ron has been a useful metal since the Egyptians began working with it five or six thousand years ago. His - torians believe Egyptians got their iron from meteorites. Production was a closely guarded secret because it was the best metal available at the time for making weapons and tools, but histori- ans have also found what they think are sites where iron mining and smelting took place in what is now Turkey. The people who mined and smelted iron in Turkey were enemies of Egypt named Hittites. The Hittites were known for long hair and their use of strategy and tactical skill in battle. Ramses II initially despised them, thinking they were effeminate, but he learned to respect them in battle, eventually made peace with them, and chose to marry a Hittite woman. The existence of those ancient min - ing and smelting sites are revealing. The secret of working with iron could not be kept from Egypt’s enemies for long, if only because the basic techniques were simple. However, there was still a great deal to learn about iron and how to maxi - mize its use. One disadvantage to iron was that its quality varied. Where it was mined and how the iron was extracted made a difference when making tools or weapons. Historians have found addition- al early evidence of cultures that discovered and used iron in places such as China, India, Japan, and the Middle East. In particular, the Japanese were able to create centuries-old heir- loom steel swords. European methods lagged, however. The Europeans did not understand how to heat iron to the melt- ing point. Instead, they built clay-lined ovens and used the ovens to burn wood and iron ore. The process was slow, but it caused the iron to separate from the rock, creating a slag. They would con- tinue heating and hammering the iron, a process that mixed the iron with oxygen and removed the carbon. The result was almost pure iron…easy to work with, but it couldn’t take, or keep, a good edge, and therefore was useless for weapons. It came to be known as wrought iron. In the East, iron was being melted and then cast. Cast iron contains more carbon than wrought iron, which makes it more useful for weapons. However, it is also brittle. What ultimately was needed was a way to make steel. Benjamin Huntsman took out a pat- ent in 1740 for a process to make steel springs for clocks. His process began with wrought iron. He used a blast fur- nace to melt it in a crucible made of clay, then added pure charcoal to the melted metal. This created an alloy that could be used to cast strong, flexible springs. Because of this process he developed, Benjamin Huntsman is credited with the invention of modern metallurgy. As an interesting side note, his work led to the creation of nautical chronom- eters. Mariners had been unable to navigate in a precise way because they could not figure out exactly where they were from East to West. Nautical chro- nometers made it possible for them to navigate globally for the first time with real confidence. Iron became most useful after scien- tists began to understand the chemistry involved in the process of making it, and especially the role of carbon in mak- ing iron hard. Acquiring the necessary knowledge took thousands of years. De- velopment of the periodic table helped. In the center of the periodic table, there are three metals that are consid- ered to belong to the iron family, or triad, because of their similarity to each other: iron, cobalt, and nickel. Clean cobalt has a pink tinge; clean nickel has a yellow tinge and can be given a high polish. Manufacturers use nickel as the chro- mium undercoat for chromium plating because the results are better than with iron. Cobalt and nickel also do not rust as easily as iron. Iron is the fourth most common el- ement in the crust of the earth, but it is