Income (metallurgy)

See also: Income (homonymy)

The returned is a thermal Traitement carried out on the metal parts in order to their give their mechanical characteristics and sometimes of resistance to the Corrosion of use. This treatment is carried out after the Trempe.

The income is carried out in two stages:

Reheating of the part until a certain color (yellow straw for steels) or returned;
final Cooling.

For the parts in Steel, the income is a warming of the part which makes it possible to soften the effects of hardening. It makes it possible to eliminate from the compounds weakening the parts (carbides) with the grain boundaries without deteriorating too much the fundamental effects of hardening (loss of 1 or 2 degrees of hardness). It also allows certain constraints too important to be released (by supporting the atomic migrations by rise in the temperature). These constraints and these carbides could become starters of brittle fracture as many.

The income is carried out at a temperature lower than that of hardening or annealing.

For the alloy parts of Aluminum, the treatment of income hardens the part by precipitation of made up Intermétallique S in the matrix aluminum.

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