Physical Metallurgy of Steel
Like all other metals, iron and steel are crystalline in structure, composed of atoms in a fixed lattice. As noted earlier, iron may exist in one of two cubic forms, body- centered (BCC) or face-centered (FCC). At room temperature, pure iron is composed of a body-centered cubic lattice. In this form it is known as alpha iron, also called ferrite, which is soft, ductile, and magnetic. When heated above about 1415°F (768°C), alpha iron loses its magnetism but retains its body-c