Aluminium Heat Treatment
Aluminium is the most abundant metal in the Earth's crust and its alloys must be correctly heat treated to achieve their maximum properties. Not all alloys of Aluminium benefit from heat treatment. Those which are heat treatable can achieve an increase in strength and hardness by precipitation hardening through correct heat treatment.
Solution Treatment
This is applicable to the heat treatable alloys and involves heating the alloy to the appropriate temperature to take the alloying constituents into solution. These constituents are held in solution by rapid quenching, usually in water. Subsequent heat treatment at very low temperatures i.e. results in 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.
Alloys of Aluminium are very rapidly quenched after Solution treatment The usual quenching medium is water at room temperature. In some circumstances slower quenching is desirable, where forced air blast, hot water or polymers can be used.
Finally the alloy is hardened by the process of Ageing, or Precipitation Hardening. This can involve heating the alloy up to a very low temperature <200?C and holding it there for several hours or days. Some Aluminium alloys age naturally at room temperature over several days.
Please contact the TTI Letchworth site for further detail on Aluminium Heat Treatment