Puddling

puddling: see Henry Cort.

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puddling [′pəd·liŋ]

(metallurgy)

A process for the production of wrought iron by agitation of a bath of molten pig iron with iron oxide in order to reduce the carbon, silicon, phosphorus, and manganese content.

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puddle, clay puddle, puddling

Clay to which a little water has been added and which then has been tempered, to make it homogeneous and to increase its plasticity; used to prevent the passage of water.

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puddling

1. Inducing compaction in mortar or concrete by the use of a tamping rod.

2.See puddle.

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Puddling 

a metallurgical process for the conversion of pig iron into mild, low-carbon iron, produced in a pastelike state on the hearth of an internally fired reverberatory (puddling) furnace. Puddling, which replaced bloomery conversion, was characterized by higher productivity, and it also permitted the replacement of expensive and scarce wood charcoal with coal and other types of fuel. A reverberatory furnace was used for the first time to produce wrought iron in England in 1766 by the brothers T. and D. Cranedge, who used coal as a fuel. The process was perfected in 1784 by H. Cort, who played a major role in the widespread adoption of the process.

In essence, the process requires that pigs of iron be loaded onto the hearth of a puddling furnace. The molten metal and slag found in the furnace are stirred (puddled) with metallic rods in order to increase the contact surface. The small lumps of iron formed on the furnace hearth are rolled onto a rod to form a bloom, usually 40–60 kg in weight. The bloom is then removed from the furnace, hammered, and conveyed to rolling. Puddling iron is readily welded or worked into shapes and contains little phosphorus or sulfur and few nonmetallic inclusions.

Having come into widespread use at the beginning of the 19th century, puddling was the basic method of producing large quantities of iron and steel. During the second half of the 19th century, the more advanced converter process (seeBESSEMER PROCESS) and open-hearth process of converting pig iron into steel began replacing puddling. Puddling has not been used in the USSR since the 1930’s.

REFERENCES

Metallurgiia stali. Moscow, 1961.
Ocherki istorii tekhniki v Rossii (1861–1917). Moscow, 1973.
Mezenin, N. A. Povest’ o masterakh zheleznogo dela. Moscow, 1973.

IA. D. ROZENTSVEIG