The metal invented by British metallurgist Harold Brearley in 1912 is stainless steel. Harold Brearley discovered stainless steel while working at Brown Firth Laboratories in Sheffield, England. Stainless steel is an alloy primarily composed of iron, chromium, and other elements, which gives it its corrosion-resistant properties. This invention revolutionized various industries, including manufacturing, construction, and kitchenware, due to its durability, strength, and resistance to rust and staining.