- Engineering & Materials
- Gilchrist, Percy Carlyle (1851–1935)
Gilchrist, Percy Carlyle (1851–1935)
English metallurgist who devised an inexpensive steel-making process.
Gilchrist was born in Lyme Regis, Dorset, on September 27, 1851, the son of a local barrister. He was educated at Felsted School, Essex, and later at the Royal School of Mines, where he acquired a sound knowledge of metallurgy. Between 1875 and 1877, together with his cousin Sidney Gilchrist Thomas, he developed a method of producing low-phosphorus steel from high-phosphorus British ores (reducing the need—and cost—of using special imported ores). Thomas died soon afterward but Gilchrist, who lived on for more than 50 years, became famous. He was vice president of the Iron and Steel Institute and in 1891 was elected a fellow of the Royal Society. He died on December 16, 1931.
Steel was a comparatively rare commodity until the 1850s, because its production was difficult and costly. Then in 1855 Henry Bessemer invented his converter (in which air blown through molten pig iron oxidized impurities to produce a brittle, low-carbon steel). The addition of ferro-manganese gave a tougher product, but even so only low-phosphorus iron could be used, and most British ores were too high in phosphorus.
In 1870 Sidney Gilchrist Thomas was a junior clerk working in London for the Metropolitan Police but, like his cousin, he had an intense interest in natural science and metallurgy. After attending a series of lectures at the Birkbeck Institute, he joined Percy Gilchrist in trying to manfacture cheap steel from high-phosphorus ores. They used an old cupola to make a Bessemer-type converter and lined it with dolomite. The pig iron was added and melted before being subjected to prolonged “blowing.” The oxygen in the blast of air oxidized carbon and other impurities, and the addition of lime at this stage caused the oxides to separate out as a slag on the surface of the molten metal. Continued blowing then brought about oxidation of the phosphorus, raising the temperature of the metal still further. When oxidation was complete (as judged by the color of the flames coming from the convector), the cupola was tilted and the slag run off, leaving the molten steel to be poured into ingot molds. The product became known at first as “Thomas steel,” and the age of cheap steel had arrived.
From the Hutchinson Dictionary of Scientific Biography, © RM, 2020. All rights reserved. Published under license in AccessScience, © McGraw-Hill Education, 2000–2020. Helicon Publishing is a division of RM.