Tasdiqlayman“Chet tiilar” kafedras imudiri M. B. Ganikhanova

Heat Treatment of Ferrous Materials

The properties of metals can be changed by various forms of heat treating.

Steels are affected to a greater extent by heat treating than are other materials. All

heat treatments either soften or harden a metal. The most common treatments for

softening are stress relieving, annealing, and normalizing; while the major

hardening processes are case-hardening or surface-hardening, and through - hardening. Hardening is performed by heating steel to a prescribed temperature and then quenching it in oil or water.

Quenching is the process of rapidly heated metal by immersing it in

liquids, gases or solids (such as sand, limestone, or asbestos).

Tempering is the process of reheating previously hardened steel and then

cooling it, usual by air. This increases the steel's toughness.

Annealing is the process of heating and coolling metals to soften them, release their internal stresses, and make them easier to machine.

Normalizing is achieved by heating metals and letting them cool in air to

relieve their internal stresses.