This document discusses ferrous metals and their classification. It notes that ferrous metals contain iron as their major constituent and includes metals like cast iron and steel. It then describes the different types of ferrous materials including plain carbon steels, alloy steels, and stainless steels. Plain carbon steels are further broken down into low carbon steels used for automotive bodies, medium carbon steels used for rails and gears, and high carbon steels used for cutting tools. Alloy steels add other elements like chromium and nickel to improve properties.