MCQ Detailed View

Wrought iron is a type of iron alloy that contains a very low percentage of carbon, usually less than 0.08%. In wrought iron, carbon is present primarily in the form of iron carbide (Fe₃C), also known as cementite. Iron carbide is a hard, brittle compound of iron and carbon that significantly affects the mechanical properties of iron. The presence of iron carbide contributes to the strength of wrought iron while maintaining its ductility.

Wrought iron also contains small amounts of slag, which are impurities such as silica, giving it a fibrous texture. Unlike cast iron, which has a higher carbon content (2–4%) and may contain free graphite, wrought iron is almost entirely free from graphite. Therefore, options such as graphite or silicon carbide are not correct. Graphite occurs in cast iron due to its high carbon content, while silicon carbide is not naturally present in iron alloys.

The low carbon content and uniform distribution of iron carbide make wrought iron soft, malleable, and resistant to corrosion, which is why it was historically used for making gates, railings, and tools. Iron carbide in wrought iron is finely dispersed in the iron matrix, allowing it to be easily worked and shaped without cracking.

Understanding the form of carbon in iron alloys is crucial in metallurgy and inorganic chemistry. It explains differences in mechanical properties between wrought iron, cast iron, and steel, and determines their suitability for various engineering applications. In summary, in wrought iron, carbon exists predominantly as iron carbide (Fe₃C), which controls hardness and strength while maintaining ductility.