BACKGROUND: Materials scientists can add different amounts of metals to steel to make the steel stronger or more flexible. More than 50 types of extra-strong steel for buildings, and steel coatings to prevent rust on cars, have been developed. Scientists can also produce steel that is more lightweight for cars; less weight means the car burns less fuel when operating.
WHAT IS STEEL: Steel describes an entire family of metals, all of them alloys in which iron is mixed with carbon and other elements. Steel is used in just about every area of our lives: in cars, in construction, in appliances like refrigerators and washing machines, even to make steel toecaps for protective boots and scalpels for medical surgery. Steel is environmentally quite friendly: it is easily recycled, highly durable, and uses much less energy to produce than other materials.
WHERE STEEL GETS ITS PROPERTIES: How hard steel is depends on the how much carbon is inside. For instance, the steel used to manufacture a pair of scissors contains almost 20 times as much carbon as the steel used in a soda can. But no steel contains more then 1.5 percent carbon. Heat can also affect steel's properties. If you cool a red-hot piece of steel very quickly in cold water, it will become harder and more brittle. The same piece of metal could be made softer by keeping it a high heat for a longer period of time and then cooling it slowly.
EYE ON HISTORY: Steel was invented in 1856 by a British man named Henry Bessemer, who founded his own steel mill in Sheffield, England. Steel is still produced using the same basic technology: blowing air through molten pig iron to oxidize the metal and separate impurities.