Stainless steel is a steel that contains more than 10.5% chromium. The added chromium keeps the iron in the steel from rusting and improves its heat resistant properties.
How stainless steel was discovered
This level of chromium was identified through a series of ad-hoc experiments over a number of years. According to the accepted history, Harry Brearley was investigating steels with improved wear resistance for use as gun barrels, working for Firth Rixson in Sheffield, UK.
Adding more chromium not only improved his samples' wear resistance but also improved their resistance to attack by numerous chemical solutions. He refined the experiments with the help of a friend who ran a cutlery factory. When they carried out tests normally reserved for cutlery, they found the alloys were very resistant to corrosion and staining, which gave the material its name.
Where stainless steel is used
Today stainless steel has numerous uses across dozens of industries. In architecture it is prized for its strength, rigidity and flexibility, which make it an ideal material for large buildings; examples include One World Trade Center in New York City and Waterloo Station in London. It is also widely used by doctors and other medical professionals for its anti-bacterial properties.