iron industry

iron industry. Iron has been used in the British Isles since the prehistoric Iron Age. Its importance has continued until the present day. Archaeological evidence of iron production has been found on many sites over most of Britain, wherever iron ores could be extracted with comparative ease and there was adequate fuel for smelting. Most villages employed a smith and it became the most common surname in England.

Iron production depended on the availability of smeltable ores and refining and casting techniques. For many centuries the highest-quality ore was haematite and the heat source for smelting was charcoal. Thus, for example, the weald of Sussex and the Cumbrian area, which both possessed the necessary resources, remained important centres of high-quality British production from the Middle Ages until the early 19th cent. However, mining of lower-quality ores supported the industry elsewhere.

When many areas became denuded of trees, efforts were made to find other fuels, notably coal, for smelting ores. Coal had only been used in fashioning iron previously. Experiments were undertaken by many ironmasters, including Dud Dudley in the 17th cent., but it was not until the early 18th cent. that Abraham Darby succeeded. The technique took many years to become economically worthwhile and only towards the end of the 18th cent. was coal usually used to smelt iron ores. The consequent quantity production at lower prices encouraged many developments in the uses of both wrought and cast iron.

The most famous centre of ironworking using coal was founded by Darby at Coalbrookdale (Shropshire). The adjacent iron bridge across the river Severn, designed and built by John Wilkinson, stands to this day. Wilkinson's pioneering efforts encouraged many innovators so that by the 1780s mills were erected with stressed iron members allowing height and scale in buildings, utilizing the principles of what came to be skyscraper engineering. One of the most spectacular buildings of iron was the Crystal Palace for the Great Exhibition of 1851.

Although unusual uses of iron for building purposes in the early 19th cent. impressed the public (iron-framed churches and wrought-iron Regency balconies), the more significant demands on the industry were supplying households with kitchen ranges, firebacks, and cooking utensils. During the 1830s and 1840s significant demand came from railways. These required iron for their tracks, locomotives, and as components for many kinds of equipment. The relationship of railways with the iron industry was close and continuous. However, such was the variety of demand for iron that the industry was never dominated by railway demands even at the heights of the mania in the 1840s.

Before 1850 manufacturers of many kinds of engineering products demonstrated the versatility of iron, either wrought or cast. During the 1820s, steam-engines made of iron and driving paddles gave an impetus to shipbuilding. In the middle of the century the Royal Navy received HMS Warrior, its first iron-clad warship. This was soon superseded by all-iron vessels of much greater size and mobility. From the mid-19th cent. the merchant navy ordered many iron ships, with greater speed and larger cargo capacity.

In the 1840s sheet iron plated with tin was invented. This gave rise to an industry, concentrated in south Wales and the west midlands, providing the basic material for many utensils for the kitchen, food-processing, and storage. The cutlery trade used iron for many products, reserving steel, a semi-precious metal, for cutting edges. The Bessemer process, patented in 1855, made mild steel a cheap and superior rival for wrought and cast iron in some products.

Iron continued to be in demand as the basic raw material for steel-making. However, steel had structural advantages and durability which iron lacked, and the railways adopted steel for their tracks. Research in steel manufacture produced metals for special purposes. Amongst these was stainless steel and, from the late 19th cent., a succession of armour plates evolved for warships, armoured cars, and tanks.

Iron continues to have a role in its own right for many engineering uses, ranging from building supplies to the structural beds for many machines, where its weight and strength make it ideal. Its cheapness keeps it in use. In the early 21st cent., challenges come not from other metals but from plastics.

Ian John Ernest Keil