Steel
How did steel come about?
Steel does not occur in nature: it is iron with less than 2% carbon added; the carbon atoms stop layers of iron atoms from sliding, so steel is much harder than pure iron.
Last updated:
In three stops
Where were its atoms born?
Steel's two main atoms come from two different stellar processes: iron from massive stars and supernovae, carbon from three helium nuclei fusing inside red giant stars.
How did it form on Earth?
Pure steel is not found in nature; it is man-made. Its raw materials come from nature: iron ore, coke made from coal, and limestone.
What did humans make of it?
Steel is iron containing less than 2% carbon (often just a few tenths of a percent). The carbon atoms sit in the gaps of the iron crystal and make it hard for layers of atoms to slip. Smiths learned this by trial over thousands of years; mass production began with the Bessemer process in 1856. Today the world makes about 1.9 billion tonnes of steel a year, and it is one of the most recycled materials.
Did you know?
Stainless steel contains at least 10.5% chromium. The chromium forms a thin, invisible oxide layer on the surface that protects the iron underneath from rust.
See it in the journey: Mass-produced steel (1856) →