Iron and Steel making history

The name Iron can refer to pure form, but due to history is also the name commonly used to refer to element iron with large amounts of carbon. Pig iron and cast iron contain upto 4 percent carbon by weight. Wrought iron is fairly pure iron containing glassy inclusions. Steels contain small controlled amounts of carbon. Other elements will also be added, in modern steels these can be carefully monitored and controlled. Before modern techniques the desired properties would best be achieved by trial and error, and a tacit knowledge of the materials.

Iron making process

Iron Oxide  + 	 Carbon 		-->  	Iron 	+	Carbon dioxide
(mineral)    	(wood, coal, coke)		(metal)		(gas)

The melting point of high carbon-Iron Alloys is around 1150-1200 oC

Wrought Iron

Cast iron was always too weak and brittle in tension to make tools and weapons. Pig iron directly taken from the furnace contains a high proportion of cementite, Fe_3C. By heating in air at about 800-900 oC iron oxide is formed on the outer surface of the artifact, by folding this


Hitites 16th Century BC

About 2000 B.C. the Hittites developed Iron weaopons in northern Asia Minor, a region rich in iron. In 1650 B.C. the Hittites began building a powerful empire. They extended their control in Asia Minor, seized northern Syria from the Egyptians, and expanded into northern Mesopotamia, where they conquered the Babylonians. Hittite culture was greatly influenced by contacts with the Babylonians. While they were less advanced than the peoples of Mesopotamia, they had learned to extract iron from ore - they were the first to make tools and weapons of iron. The Hittites heated iron ore and pounded out impurities before plunging it into cold water. The tools and weapons they made with iron were harder and had sharper edges than those made out of bronze or copper. Because iron was plentiful, the Hittites were able to arm more people at less expense.

The Hittites tried to keep this valuable technology secret. But as their empire collapsed about 1200 B.C., Hittite ironsmiths migrated to serve customers elsewhere. The new knowledge thus spread across Asia, Africa, and Europe, ushering in the Iron Age.


Iron was greatly prized at this time as can be seen by the Iron dagger wrapped into the bandages of the mummfied remains of the Pharoah.

Greeks - Reference to Quenching iron in the Odyssey (Odyssey IX 393 tr. E V Rieu)

The greek poet Homer is credited with writing the Iliad and the Odyssey around 800 BC

"Siezing the olive pole, they drove its sharpened end into the Cyclops' eye... [which] hissed around the olive stake in the same way that an axe or adze hisses when a smith plunges it into cold water to quench and strengthen the iron.

Romans 2nd Century AD

Pausanius writes "Theodorus of Samos was the first to discover how to pour or melt iron and make statues of it."

Japanese Sword Making

Swords of a high degree of craftmanship are made from the 9th Century AD, with metel made by repeated fold and forge technique. Since repeated heating and folding causes reduction of carbides by oxygen in the air these swords are made with controlled carbon levels, so it would be fair to say they are steel rather than iron.

The Japanese where no the only ones to develop these techniques, although they did achieve a high degree of craftsmanship.

Britains - 15th Century AD

Furnaces with a blast of air built in Britain.

Construction of Iron Bridge 1779

This followed development and expansion of pig iron and cast iron production. Three generations of Abraham Darby's together they introduced the use of charcoal and were responsible for constuction of iron Bridge. Note that the bridge is constructed to use the cast iron in compression, since the cast iron used was relatively weak and brittle in tension.

With the much cheaper Coke being used, total costs were reduced and iron production in England relocated to the coalfields. Being a purer form of carbon than coal fewer imprities are introduced.

Crucible Steel

Crucible technique or puddling - the original steel making technique, developed in India as wootz (300AD), used in the Middle East as Damascus steel (1000AD) and independently redeveloped in Sheffield by Benjamin Huntsman in 1740AD, and Pavel Anosov in Russia in 1837AD.

Puddled Wrought Iron

Henry Cort patented the puddling process. Pig iron is melted and reacted with Iron oxide, which was stired with a tool called a rabble. A skilled puddler could produce upto a ton or iron per day. The steam ship 'Great Britain' designed by Isambard Kingdom Brunel and built in 1843 was produced from puddled wrought iron.

Bessemer Process - 1856

Sir Henry Bessemer's converter is invented, in which excess carbon is removed by reaction with air. A 30 tonnes pear shaped vessel is filled with pig iron and air is forced through the bottom. First silicon and manganese are oxidised and form a 'slag', then carbon is oxidised, producing mainly carbon monoxide and heat (scrap steel can be melted to use this heat). Sulphur isn't removed, but addition of manganese into the molten metal, introduced by Robert Mushet, can prevent formation of deliterious FeS. With the introducion of the Bessemer process the price of steel fell by a factor of 10, but it was 30 years before mild steel production surpassed production of puddled wrought iron.

Open Hearth process

Developed by Sir William Siemens (1823-1883) and Fredrick Siemens (1826-1904). Similar to puddling process but on a much larger scale, with recycling of heat using a labyrinth of brickwork, which is heated with the exhaust gases before changing the direction of flow and using it to preheat the incoming air. This process became viable only as the amount of steel produced from scarp increased, since the Bessemer process only produces enough heat in the vessel to use arounf 5% scarp in produciton.

Firth of Forth Bridge 1889

Contains 50,000 tons of steel and still in use over 1 century later. Painted continously.

Modern Steelmaking

The bessemer process has been modified so that oxygen is now used instead of air (Basic Oxygen Steelmaking BOS), also electric furnaces of different types are available to melt scrap steel.