Aluminium 2618A is a high strength alloy containing both copper (2%) and magnesium (1.5%), imparting good machinability and a fair resistance to atmospheric attack. Due to its ability to work in higher temperatures applications, 2618A is commonly used for pistons and rotating aircraft parts. Whilst traditionally an aerospace alloy, it has become very popular in the prodsuction of motor racing pistons and other critical high technology applications.
Chemical Composition
Si 0.25 max
Fe 0.9 – 1.3
Cu 1.9 – 2.7
Mg 1.3 – 1.8
Ni 0.9 – 1.2
Ti 0.04 – 0.1
Al Balance
Remainder Each 0.05 max
Remainder Total 0.15 max
2618A is an Al-Cu-Mg-Fe-Ni series heat-resistant forging aluminium alloy, which can be strengthened by heat treatment. The chemical composition of the alloy is similar to that of 2A70 alloy, and its properties are similar to that of 2A70 alloy. It has high heat resistance and good cold and hot working performance. The corrosion resistance of the alloy is obviously improved after solution treatment and artificial aging, but there is a tendency of intergranular corrosion. Its weldability is medium and its machinability is good.
2618A aluminium alloy is used to manufacture piston of internal combustion engine and complex forgings working at 200-250 ℃, such as compressor impeller, blower impeller, tire mould, high temperature working parts of aircraft engine, etc.
When 2618A aluminium alloy is treated by solid solution heat treatment, the heating temperature of solid solution should be strictly controlled. When the temperature reaches the upper limit, the grain size of aluminium alloy will grow easily, and it is close to the dangerous temperature of overheating of aluminium alloy.
The temperature of the cooling medium has an effect on the mechanical properties and hardness of the alloy, and the water temperature should not be higher than 40 ℃ during quenching.
2618A aluminium alloy has good technological plasticity under reheating condition. It can be used to manufacture various free forgings and die forgings by hammer forging and hydraulic press. Forging temperature is 450-350 ℃.