Tempers

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PUESTA EN SOLUBILIZACIÓN

Se hace a temperatura elevada del orden de 530º C para las aleaciones de la familia 6000 (Simagaltok/Al-Mg-Si). Esta temperatura es más elevada cuando la aleación está cargada de los elementos aleantes; magnesio y silicio. La duración de mantenimiento a temperatura depende del espesor de los productos.

Durante el mantenimiento prolongado a temperaturas elevadas, loscompuestos intermetálicos del tipo Mg2Si para las aleaciones de la serie 6000, de tipo Al2Cu para los de la familia 2000, se redisuelven y la aleación forma entonces una solución sólida homogénea.

La temperatura de puesta en solución de las aleaciones de aluminio de endurecimiento estructural deben ser reguladas con precisión para no alcanzar la de las eutécticas. Para las temperaturaseutécticas se produce una fusión local de los compuestos intermetálicos y de los eutécticos (aleaciones con punto de fusión bajo). El metal es entonces inutilizable. Según su composición, esta temperatura se sitúa entre 555º y 620ºC para las aleaciones de la familia 6000.

Before Solution Heat Treatment
CuAL2 Lies in large particles along the grain boundaries.
Aluminium can absorb small amounts ofcopper in solution at room temperatures. With an increase in temperature more copper is absorbed in solution.
There is a similarity when one dissolves sugar or copper sulfate crystals in water. More crystals can be dissolved in hot water than in cold water. If as many crystals as possible are dissolved in hot water and the water allowed to cool then the crystals will precipitate out of thesolution.
In solution heat-treating we are carrying out a similar process. The larger proportion of copper is absorbed in the aluminium at elevated temperatures.
Quenching in cold water then rapidly cools the hot metal. This holds the saturated solution of copper in the alloy.

After Solution Heat Treatment
Cu AL2 is now dispersed in very fine particles uniformly throughout the grain.This condition however is only temporary as the copper still precipitates out of solution the process is known as age hardening because as the copper precipitates out in small particles, evenly, and these form in the slip planes making the metal harder and stronger. This process takes about 4 days.

In the mean time the metal is in a soft, workable condition for about 20 minutes. It reaches 90%to 98% of its maximum hardness in 4 hours. This age hardening process may be halted if the newly treated metal is kept at temperatures below the freezing point of water.
Solution heat-treating puts the copper in the alloy in solid solution with the aluminium. It is then soft. After solution heat-treating, if the metal is allowed to reach temperatures above freezing, the metal age hardens to itsstrongest and hardest condition.
The age hardening process can be achieved artificially by Precipitation Heat-Treating (Artificial Ageing). The artificial ageing accomplished by precipitation heat-treating does a better and more even job than the natural method and with some alloys; the full hardness cannot be achieved without precipitation heat treatment.
The temperatures and soaking timesshown on the tables are critical. If not then the solution and or precipitated alloy will contain pieces of free copper, which will cause intergranular corrosion
Solution Heat Treatment
This is applicable to the heat treatable alloys and involves a heat treatment process whereby the alloying constituents are taken into solution and retained by rapid quenching. Subsequent heat treatment at towertemperatures i.e. ageing or natural ageing at room temperature allows for a controlled precipitation of the constituents thereby achieving increased hardness and strength.
Time at temperature for solution treatment depends on the type of alloy and the furnace load. Sufficient time must be allowed to take the alloys into solution if optimum properties are to be obtained.
The solution treatment...
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