Metallurgy for the Nonmetallurgist with an Introduction to Surface Finish Measurement
This chapter deals with a discussion of general topics regarding structure and properties that are common to all metals. The metallic bonding between the neighboring atoms in the crystal lattice is somewhat different from chemical bonding and gives rise to the inherent strength and malleability of the metals, properties not exhibited by other chemical compounds. The individual crystals in a polycrystalline metal are called grains, and the contact regions between adjacent grains are called grain boundaries. In a properly manufactured and processed metal, the grain boundaries are stronger than the grains themselves; and when the metal is broken, failure occurs transgranularly, or through the grain. Mechanical properties are those that can be drastically changed by processing and thermal treatment. Such characteristics as hardness, strength, ductility, and toughness are the properties that govern the performance of the metal in use.