This document discusses ferrous metals and their classification. It states that ferrous metals contain iron as their major constituent, with examples including cast iron and steel. It then describes the classification of ferrous materials, with steels being alloys of iron and carbon. Steels are further classified as plain carbon steels, which contain up to 1.5% carbon, and alloy steels, which contain additional alloying elements. Plain carbon steels are then broken down into low-carbon (<0.25% C), medium-carbon (0.25-0.6% C), and high-carbon (>0.6% C) steels.