Who developed the Bessemer process for steelmaking?

Henry Bessemer developed the Bessemer process for steelmaking. He patented the method in 1856 after working on a way to produce inexpensive steel in quantities suitable for military guns and industrial construction.

The process blew air through molten pig iron inside a large converter. Oxygen in the air oxidized impurities, especially excess carbon, and the resulting heat kept the metal molten. This made it possible to convert large batches of iron into steel in roughly 10 to 20 minutes, dramatically reducing production costs.

Bessemer was not the only person to explore this idea. American inventor William Kelly developed a similar pneumatic process, and Robert Forester Mushet later improved the final steel by controlling its carbon and manganese content. Even so, Bessemer's practical, commercial system became the standard reference and is the canonical answer to this question.

The process helped make steel widely available for railway rails, bridges, buildings, ships, and machinery. It was eventually replaced by open-hearth and basic-oxygen methods, which offered better control over the steel's chemistry.