Steel and Metallurgy

Metallurgy — the science and technology of metals — began approximately 7,000 BCE with copper smelting and progressed through bronze (copper + tin, enabling harder tools and weapons, c. 3,300 BCE) to iron (c. 1,200 BCE) to steel (iron with controlled carbon content) to modern alloys. Each transition enabled new technologies and social changes — the Bronze Age and Iron Age are named for these pivotal materials. Modern steel (produced via the Bessemer process, 1856) enabled the Industrial Revolution's railways, bridges, and buildings. Steel production is currently 1.9 billion tonnes per year — the most produced metal by far. The Bessemer process reduced steel's cost by 80% in 20 years, making it affordable for mass construction. The Brooklyn Bridge (1883), Eiffel Tower (1889), and Empire State Building (1931) were all made possible by cheap steel. Today, high-strength steels, stainless steel, and specialty alloys enable aerospace, medical implants, and precision manufacturing.