
266 Engineering Materials Technology
pearlite microstructure, the hardness and strength being slightly greater than
that which would have occurred with full annealing.
12.9 Selecting heat treatment
Heat treatment can be defined as the controlled heating and cooling of metals
for the purpose of altering their mechanical properties. While heat treatment is
often used to strengthen or harden a steel there are numerous occasions when
heat treatment is used to prepare the material for fabrication, e.g. machining or
restoring ductility so that deformation can continue. Full annealing, process
annealing, spheroidizing annealing and normalizing ar