All castings must undergo a heat treatment to achieve the specified mechanical properties. Unless otherwise stated in the survey and order or agreed upon between the buyer and the manufacturer, all cast parts, must be properly “heat treated to make them tough and ductile. This treatment consists of uniformly heat the castings to a suitable temperature, holding them until they are evenly heated throughout, and their temper with a minimum time lag in water for a minimum temperature of 1 040 c. The water must be stirred so as to avoid the formation of a blanket of steam around flows during tempering. In the case of students from 4 castings, alternatively they can be cooled air to the top 1 040 c If the maximum cutting thickness does not exceed 60 mm and if so agreed between the parties. All test bars must be properly marked identify with the castings they represent.
1 all castings, shall be free from defects that harm machining or usefulness of castings.
2 when it is necessary to remove the throws or doors to flame or arc, or a combination thereof, or by any 2
3 castings, must be heat-treated in a well built oven, with adequate means of temperature control, which would enable all castings to be heated uniformly to the necessary temperature.
Technology of aluminium alloy heat treatment is divided into the following four categories
Annealing treatment of aluminium alloy heat treatment ：Heated castings to high temperature (about 300℃)，after insulation ，technology of furnace cooling ,called anneal. Annealing treatment can eliminate innerstress of castings ，stabilize size of castings，increase plasticity of castings.
Solution treatment of aluminium alloy heat treatment: The casting is heated to high temperatures as much as possible，rapid cooling after heat preservation for long enough time. Solution treatment can improve the strength and plasticity of castings，perfect decay resistance of alloy.
Aging treatment of aluminium alloy heat treatment: Adopt aging treatment of lower aging temperature or shorter soaking time,called incomplete artificial aging. Adopt aging treatment of higher aging temperature or longer soaking time ，called complete artificial aging. Incomplete artificial aging can make castings get better synthesized mechanical property，that is to say ,higher strength，better plasticity and tenacity，but maybe corrosion stability is lower.
Complete artificial aging can make castings get largest strength，that is to say，largest strength of extension, elongation is lower.
The passage above talks about process classification and effects of aluminium alloy heat treatment.