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Phosphoric iron

Metal

Phosphoric iron

Phosphoric iron

Iron with sufficient phosphorus present to increase the hardness of the metal. As well as increasing the hardness, phosphorus also increases the rate of work hardening of the metal, and its brittleness. In 17th-18th century Britain, phosphoric iron was referred to as ‘cold-short’, since it tended to crack during cold forging, but was preferred for nailmaking due to its hardness. Phosphorus also increases the drawability of low-carbon wrought iron, phosphoric iron being used for the wires of musical instruments (Goodway 1999 [JHMS, 33.2, 104-5]
The presence of phosphoritic iron may be revealed under the microscope by excessive grain size (when little or no carbon is present) and/or ghost structures when some carbon is present in the metal.