Question

What machine could produce steel cheap and strong

Answer 1

During the Industrial Revolution, steel was made in machines called Blast Furnaces.
It wasn't until around 1856, when Henry Bessemer create a process called the Bessemer Process, that made steel cheap and quick to make.

In the Bessemer Process, molten iron is converted to steel by blowing air through it after it was removed from the furnace. The air blast burned the carbon and silicon out of the iron, releasing heat and causing the temperature of the molten metal to rise.

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