New Metals on Demand

An alloy is a material consisting of two elements, at least one of which is a metal, with properties different from any of its constituent parts. Most of the early alloys known to and used by humans, such as bronze, brass, and pewter, had been discovered accidentally. By the late 19th century, however, scientists had begun to realize that they were capable of designing a variety of alloys with special properties needed for the host of metallic products then being produced. At first, their attention focused on alloys of iron. 

Iron hadbeen known and used for the manufacture of products as early as about 1200 b.c.e. in some parts of the world. The iron used during this period usually occurred in a form known as wrought iron. Wrought iron is a relatively pure form of iron, containing no more than about 1 percent carbon, the most common impurity in iron. The carbon in wrought iron, along with other impurities, can be removed rather easily simply by hammering the metal while it is still soft. The product of this process has many desirable properties, but the method by which it is produced is very labor intensive and can be used for the production of only certain sizes and shapes of iron. 

By the mid-19th century, scientists and industrialists had finally begun to understand the role of carhon and certain other impurities in determining the properties of iron made by various processes. They realized that the iron needed for construction projects needed to have enough carhon in it to make it strong and malleable, hut not so much as to make it brittle. Such a product soon became known as 

Bessemer was born in Charlton, Hertfordshire, England, on January 19, 1813. Bessemer s father was the son of an engineer, and Bessemer inherited his father s interests in making new kinds of devices. One of his first inventions was a device he made when he was 17 years old for stamping deeds that saved the British government more than 100,000 (about 450,000) a year. Much to Bessemer s disappointment, however, the government failed to compensate him for the invention. 

The problem was that cannon were then made with cast iron, a form of iron that contains relatively large amounts of carbon. Cast iron is very hard, but it breaks very easily. The only substitute available for cast iron at the time was wrought iron, which is nearly pure iron. Wrought iron, however, was not suitable for making cannon (or almost anything else) because it was too soft. 

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