Aluminium alloys

From the reduction centre the pigs of aluminium are remelted and cast into ingots of commercial purity. Aluminium alloys are made by adding specified amounts of alloying elements to molten aluminium. Some alloys,such as magnesium and zinc,can be added directly to the melt,but higher-melting-point elements such as copper and manganese have to be introduced in stages. Aluminium and aluminium alloys are produced for industry in two broad groups:
1.Materials suitable for casting
2.Materials for the further mechanical production of plate sheet and strip,bars,tubes and extruded sections.
In addition both cast and wrought materials can be subdivided according to the method by which their mechanical properties are improved: Non-heat-treatable alloys Wrought alloys,including pure aluminium,gain in strength by cold working such as rolling,pressing,beating and any similar type of process.
Heat-treatable alloys These are strengthened by controlled heating and cooling followed by ageing at either room temperature or at 100–200 °C.
The most commonly used elements in aluminium alloys are copper,manganese,silicon,magnesium and zinc. The manufacturers can supply these materials in a variety of conditions. The non-heat-treatable alloys can be supplied either as fabricated (F),annealed (O) or strain hardened (H1,H2,H3). The heat-treatable alloys can be supplied as fabricated (F) or annealed (O),or, depending on the alloy,in variations of the heat treatment processes (T3,T4,T5,T6,T8).