chapter  9
68 Pages

Quenching and Quenching Technology

List of Symbols ..................................................................................................................601

References .......................................................................................................................... 602

The outstanding importance of steels in engineering is based on their ability to change

mechanical properties over a wide range when subjected to controlled heat treatment. For

unalloyed carbon steels, for example, the hardness can be increased by up to 500% just by

changing the cooling rate from the austenitizing temperature from extremely slow to

extremely fast. However quenching at a rate faster than in still air does not only determine

the desired mechanical properties but is an important side effect of quenching is the formation

of thermal and transformational stresses that lead to changes in size and shape and thus may

result in quenching cracks that damage the workpiece.