Year of Invention: 1856
What Is It? A hard compound made when carbon is mixed with iron.
Who Invented It? Henry Bessemer (in Sheffield, England)
The modern world is built on steel. Steel made modern cities possible. Bridges, skyscrapers, malls, schools, car and truck frames, and towers are automatically built on frames of steel. Dollar for dollar and pound for pound, there is no better construction material available.
Steel was accidentally discovered (but not named steel) shortly after the rise of iron (around 200 B.C.). At that time, iron craftsmen occasionally produced what they called super-hard iron (steel). However, they did not understand what turned regular iron into steel, and they were unable to control the process of forging steel.
Steel was viewed as a rare and mysterious hit-or-miss thing. Up through the Middle Ages builders worked with iron or bronze. By the fourteenth century, craftsmen had learned how to “case harden” iron (make its surface harder). A forged iron sword (for example) would be reheated while packed in coal or charcoal. This process hardened the edge. (Actually this process created a thin steel coating over the blade.)
In 1740, Benjamin Huntsman (a Doncaster, England, clockmaker) stumbled onto a process for producing weak steel. He case hardened iron strips and then melted them in a clay crucible. He called it crucible steel. He could only create it in small batches and found that it was only slightly stronger than iron.
By the beginning of the nineteenth century, engineers had learned how to make steel. The smelter mixed iron ore with charcoal in a small smelting furnace to produce cast iron. But cast iron was brittle because it had way too much carbon in it. Cast iron was then reheated in a blast furnace to remove the carbon. This produced wrought iron. Wrought iron was malleable and decorative, but too soft for construction or armor.