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More than 5000 entries on the history, culture and life of Britain (published in 1993 by Macmillan, now out of print)
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iron and steel
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New developments in metal technology from the 18C played an important part in Britain's lead in the *Industrial Revolution. Early ironworks were invariably sited in forests because the smelting process required large quantities of charcoal. This dependence ended with the discovery by the Darby family (commemorated at *Ironbridge) that cast iron, also called pig iron, could be smelted with coke. Wrought iron made a similar advance with the puddling technique (a heating and stirring process which isolated a hard core of almost pure iron), patented in 1784 by Henry Cort (1740–1800).
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Cort also introduced the system of passing the hot metal through rollers, eliminating the need for much of the hammering. These two developments left the rapidly developing industries of the early 19C with a choice between cast iron (hard but brittle) and wrought iron (strong, in the sense of resisting shocks, but relatively soft). New applications, such as railway tracks, required a material both hard and strong. The answer was steel – iron strengthened with a small proportion of carbon.
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Steel was already being produced in small quantities (for items such as cutlery and in particular at *Sheffield) by cottage-industry methods involving somewhat haphazard regulation of the carbon content of the iron. Mass production of a reliable product was made possible from the 1850s by the *Bessemer process, in which the entire carbon content of the molten iron was removed and the required proportion then reintroduced. Further improvement followed in the 1860s with the open-hearth method of *Siemens, in which a higher and better-controlled temperature in the furnace enabled the process to be stopped as soon as the carbon content was correct.
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The third stage in the growth of the 19C steel industry was the development in the 1870s by Sidney Thomas (1850–85) and his cousin Percy Gilchrist (1851–1935) of a furnace lining which made possible the use of more widely available iron ores with a high phosphorus content.
These techniques gave Britain a strong lead in world steel production in the late 19C. By the 1920s this had been eroded by foreign competition.
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