Wrought Aluminium Alloys
Extrusion ingots and sheets are cast through semi-continuous direct chill method. The sheet ingots are scalped in which about 12 millimeter of ingot surface is eliminated. The scappled ingots are preheated to homogenise the structure via heating to a high temperature and soaking there for 10-24 hours. The preheating is done at a temperature below the lowest melting point of the constituents. The ingots are after that hot rolled to about 75 millimeter thickness in 4 high reversed rolling stand. Afterward the rolled sheet is additional reheated to the similar temperature and further hot rolled to 18 millimeter to 25 millimeter thickness. Further thickness reduction might be achieved via cold rolling. The products acquired this way are termed wrought alloys and usually are inform of sheet, rod, plate, and wire and extruded sections.
The wrought alloys are called by a four digit code out of that the first digit indicates the aluminium purity as if pure aluminium otherwise the main alloying element. The second digit shows the alloy modification. The third and fourth digit implies the minimum amount of aluminium in the alloy. The first digit implies following as:
i. Aluminium is pure no alloying element.
ii. Alloying element copper but magnesium is added also.
iii. Alloying element manganese.
iv. Alloying element silicon.
v. Alloying element magnesium.
vi. Main alloying elements are silicon and magnesium.
vii. Main alloying elements are: copper, magnesium and zinc.