Материаловедение: свойства металлов. Матросова Т.А - 40 стр.

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40
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.
Case Hardening is the process of hardening thin outside layer of a metal. The
outer layer placed in contact with carbon or nitrogen compounds that are absorbed
by the metal as it is heated; afterward, the metal is quenched.
Flame Hardening is the method of harden by heating a metal to within a
prescribed temperature range with a flame and then quenching metal.
Stress relieving is used to relieve stresses that remain locked in a structure,
usually as a consequence of some manufacturing process. It involves heating to a
temperature below the critical temperature and cooling slowly. This process is
particularly applicable after straightening and cold-working operations and either
prior to or after heat treatments to reduce distortion. In stress relieving, no change in
microstructure is involved, but residual stresses are markedly reduced and
toughness is improved. The relief of locked-in stresses is a time-temperature
phenomenon.
When consideration is given to the simplicity of the stress-relieving operation
and the equipment required, this important process, which can save considerable
amounts of straightening and reworking time, cannot be overlooked. It may be
applied to relieve stresses induced by
casting, quenching, normalizing, machining,
cold working, or welding.
Glossary
№ English word Translation
1. ferrous железистый («черный»)
2. property свойство
3. affect влиять
4. heat treatment термообработка
5. soften размягчать
6. harden упрочнять
7. stress relieving снятие напряжений
8. annealing отжиг
9. normalizing нормализация
10. case-hardening местная закалка

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