Kelly, William (1811–1888)

US metallurgist, arguably the original inventor of the ‘air-boiling process’ for making steel, known universally as the Bessemer process.

Kelly was born in Pittsburgh, Pennsylvania. Having bought iron-ore lands and a furnace in Eddyville, Kentucky, he developed his steel-making process in the 1850s. Steel under the Kelly patent was first produced commercially 1864, but by then Kelly had sold his patent. He founded an axemaking business in Louisville, Kentucky, and remained in relative obscurity in spite of his invention, which became known under Henry Bessemer's name.

Experimenting, Kelly found that contrary to all ironmakers' beliefs, molten iron containing sufficient carbon became much hotter when air was blown on to it. An air blast can burn out 3–5% of carbon contained in molten cast iron. Here the carbon itself is acting as a fuel. When he heard that Bessemer had been granted a US patent on the same process, Kelly immediately applied for a patent and managed 1857 to convince the Patent Office that he was the original inventor.

After he had sold the patent, Kelly built a tilting type of converter, which produced soft steel cheaply for the first time and in large quantities. It was used for rails, bars, and structural shapes.