A fibrous ferrous material consisting of approximately 1 to 4% by weight of a slag component dispersed as elongated stringers in a matrix of low-carbon steel or iron. The slag consists mostly of iron oxide and some silica. The analysis of the iron matrix is about 0.03% carbon, 0.05% manganese, 0.10% phosphorus, 0.020% sulfur, and 0.01% silicon; the remainder is iron. Wrought iron can be identified by macroetch examination, which reveals numerous small stringers of non-metallic slag throughout the metal section.
The term iron is commonly used to describe a number of different ferrous materials. Wrought iron is different from any of the other ferrous metals, such as commercially pure iron, steel, or cast iron. The non-rusting slag fibers in wrought iron are responsible for this difference. Pure iron, steel, and cast iron do not contain slag.