English Inventor Henry Bessemer Develops Process to Produce Inexpensive Steel

views updated

English Inventor Henry Bessemer Develops Process to Produce Inexpensive Steel

Overview

In 1856, Henry Bessemer (1813-1898) developed a new method for manufacturing steel. The Bessemer process made possible the manufacture of large amounts of high-quality steel for the first time. This, in turn, provided steel at relatively low cost to various industries. By revolutionizing the steel industry, the Bessemer process helped to spur on the Industrial Revolution. Within a few decades, foundries were making railroad track, bridge girders, locomotives, armor plating, and other steel-based products.

Background

Iron has been known to man for several thousands of years; the earliest iron implements found thus far are from Egypt and were made about 3000 b.c.. However, iron is a relatively soft and brittle metal on its own. By about 1000 b.c. the Greeks had discovered that heating iron would help to harden it, but it was still brittle and not very useful for any tasks requiring strength. Other cultures heated iron ore and charcoal together, making what we now call wrought iron.

During the fourteenth century, pig iron was developed. Pig iron is made by heating iron bars, coal coke, and limestone together in a fire or furnace. First the iron ore is covered with the coke and limestone and heated for up to a week, allowing the carbon to diffuse into the surface of the iron. Then, the metal is hammered and folded in order to mix the carbon throughout the iron in the same way that kneading bread distributes the yeast throughout the dough. Unfortunately, this process was time- and labor-intensive and produced steel of varying quality.

Heating these ingredients together in a crucible was the next innovation. By allowing some degree of mixing during the heating, this process produced a more uniform quality of steel, although still in limited quantities. Even so, this method allowed one city in England to increase its steel production from about 200 tons annually to over 20,000 tons per year within a century.

The next breakthrough came in 1856 when Henry Bessemer developed the process for steelmaking named for him. In fact, unknown to Bessemer, this method of making steel was developed nearly simultaneously by the American William Kelly (1811-1888). However, Bessemer filed his United States patent application first and has received the majority of the credit. In the Bessemer process, air is continuously forced through the steel while it is contained in the crucible. This burned the carbon present in the steel, raising the temperature, and removing many of the impurities that would otherwise impair the quality and strength of the final metal. In addition, Bessemer's converters (now also called blast furnaces because of the large volumes of air that are blasted through the molten steel) ran continuously rather than in batches as was the case with crucible steel. This produced larger quantities of steel, another improvement. In this process, some carbon remains in the steel, helping to make the steel both stronger and more flexible than the original iron.

The Bessemer process has proved nearly as durable as the steel it produces. After nearly 150 years it is still the primary method of steel manufacture in the world. Other manufacturing processes are used, but mostly for specific types of steel requiring different properties. In addition, although steel today is similar to that of the 1860s, a number of specialty steels have been developed. Some examples of these are stainless steel, tool steel, spring steel, and special alloys used in extreme environments (such as jet engines, nuclear reactors, inside the human body, and so forth).

Impact

The impact of the availability of inexpensive, high-quality steel can hardly be overstated. The nineteenth century in Europe was the time of the Industrial Revolution. The development of the steam engine into a useful device, the development of the railroad, and the internal combustion engine all occurred during this century. These devices were made more efficient by Bessemer's steel. And this new steel also made other innovations possible. The importance of Bessemer's steel soon became apparent in the areas of industry and commerce, civil engineering, and the military.

Industry was the first and most obvious beneficiary of the new steel. Steel production in Britain increased from about 50,000 tons to over 1.3 million tons annually in just 25 years. At the same time, the price of this steel dropped to half of its previous level. Much of this extra steel went to industry. Some of the steel was used for infrastructure, for making the machines that made the goods that were sent to market. Using steel instead of iron, wood, or other materials helped to increase the lifespan of manufacturing devices, in the end making the manufacturing process more efficient. In addition, the greater strength of steel made some devices possible that simply could not be constructed before. Steel blades or cutting surfaces helped make saws last longer, reducing the cost of manufacturing wood products, while steel tools and parts helped make possible high-speed lathes. Also, industry could use steel in the products it made for consumers. Steel was harder than iron, less expensive than wrought iron, and more durable than wood, stone, or glass. While not the perfect material for all uses, its versatility was impressive.

All of these attributes make steel an important part of any national economy. The availability of durable and relatively inexpensive steel products to consumers encourages purchasing, thereby fueling the supply-and-demand market economy. High-quality, low-cost manufactured goods can be exported, bringing foreign currency into a country. Steel is one of the cornerstones of a healthy industrial economy, and steel plants are among the first major purchases made by developing nations as they become industrialized. It is also worth noting that, in the 1990s alone, a number of trade disputes revolved around allegations of "dumping" steel into foreign markets at artificially low prices to gain economic advantage or, in some cases, to try to hurt another nation's steel manufacturing industry. That such practices occur is yet another indication of the economic importance of steel to nations.

Steel was also important in the making of many industrial empires. In the United States, Andrew Carnegie made his fortune selling steel to the developing nation. Steel from Carnegie's furnaces went into the trains traveling to the American frontier, it built the rails they rode on, and the guns the passengers carried. In Germany, the industrial empire of the Krupp family was built, in part, on steel and steel products. Best known for supplying weapons to Nazi Germany, Krupp also built farming equipment and vehicles for many years until they were split up by the Allies after World War II.

Steel has also had a major impact on civil engineering and architecture. Without steel there would be no skyscrapers, no suspension bridges, no railroads, no reinforced concrete, and no modern highways. The strength and relative lightness of steel have made all of these things possible. It is safe to say that no large city would look the same without steel.

One of Bessemer's reasons for developing an improved steel manufacturing process was the need for more guns by British troops during the Crimean War. Among the first products he made with his new steel were guns, along with railroad track. Guns are, of course, directly useful by the military and, by allowing more rapid troop mobilization, the railroad helped to revolutionize warfare. During the American Civil War the superiority of the Northern rail system combined with the North's industrial strength helped the northern states win the war.

Other uses to which steel was quickly put were armor for vehicles, stronger gun barrels for artillery pieces, motor vehicles, naval ships, engines and turbines, and, later, tanks and parts of airplanes. As in so many other areas, it is hard to conceive of modern warfare without steel.

Although steel is being supplanted in some areas by polymers, ceramics, composites, and other materials, it still plays a vital role in modern society. While some automobiles are now made with polymer body panels, for example, steel is used for horizontal surfaces and for reinforcement within the doors because of its superior strength and ability to protect passengers during an accident. The computer and keyboard on which these words are typed are composed largely of plastic, silicon, and copper, but the assembly line on which they were manufactured is made with steel. Steel may, at some point in time, be replaced with other materials, but that time is not likely to be in the near future. In the meantime, there can be no doubt that the world we live in would be profoundly different without the availability of inexpensive and high-quality steel.

P. ANDREW KARAM