Harry Brearley was born in Sheffield in 1871, the son of a steelworker. In 1912, as an employee of Firth Brown Laboratories, of Sheffield, he was charged with finding a material that would resist the erosion caused in armaments production at high temperatures. He began to examine the addition of chromium to a standard carbon steel, and he discovered an alloy that showed no signs of rusting after being exposed to air and water. He called it "rustless steel", but this was soon changed to "stainless steel".
Brearley is conventionally credited with the invention of stainless steel, and Wikipedia describes his product as "the first true stainless steel". But (as with many so–called 'inventions'), others before him had been experimenting since 1798 with the use of chromium to produce alloys that resisted corrosion. According to Wikipedia, the German industrial concern Krupp, as well as various Sheffield steelmakers, were producing chromium steel in the 1840s, and Krupp used it in cannons in the 1850s.
Brearley was one of the first people to realise the potential of stainless steel for use in the mass production of cutlery, and other items used in the preparation of food, such as saucepans. Up to that time, the standard carbon–steel knives had been prone to rusting, and any that avoided the problem (silver or EPNS) were unaffordable to the general public.
Wikipedia describes Brearley's invention as a "martensitic" stainless steel alloy. Elsewhere it explains that the martensitic variety is one of four main types of stainless steel, but at this point it's getting far too technical for me!
© Haydn Thompson 2021