Aluminum is silver-white metal. Melting point 650 ° C. Aluminum has a crystalline fcc lattice. Aluminum has an electrical conductivity of 65% of the electrical conductivity of copper. Aluminum takes the third place in the distribution in the earth’s crust after oxygen and silicon. Aluminum is resistant to atmospheric corrosion due to the formation of a dense oxide film on its surface. The most important feature of aluminum is a low density of 2.7 g / cm3 versus 7.8 g / cm3 for iron and 8.94 g / cm3 for copper. Has good heat and electrical conductivity. Well processed by pressure.
It is marked with the letter A and with a number indicating the aluminum content. Aluminum of special purity has the mark A999 – the content of Al in this brand is 99.999%. Aluminum of high purity – A99, A95 contain Al 99.99% and 99.95% respectively. Technical aluminum – A85, A8, A7, etc.
It is used in the electrical industry for the manufacture of current conductors, in the food and chemical industries. Aluminum is not stable in acidic and alkaline environment, therefore aluminum dishes are not used for marinades, pickles, fermented milk products. It is used as a deoxidizer in the production of steel, for aluminizing parts in order to increase their heat resistance. In its pure form is used rarely because of low strength – 50 MPa.
Deformable aluminum alloys
Depending on the possibility of thermal hardening, deformable aluminum alloys are divided into not hardened and hardened by thermal treatment.
Alloys that are not refractory t / o include alloys Al c Mn (AMc1), and alloys Al c Mg (AMg 2, AMg3). The figure is the conventional number of the brand.
These alloys are well welded, have high plastic properties and corrosion resistance, but low strength. These alloys harden. Alloys of this group have found application as a sheet material used for the manufacture of complex products in the form of cold and hot stamping and rolling. Products obtained by deep drawing, rivets, frames, etc.
Alloys, hardened t / o, are widely used in mechanical engineering, especially in aircraft construction, because Have a low specific gravity at sufficiently high mechanical properties.
Duralumin – the main alloying components – copper and magnesium:
D1 – blades of propellers, D16 – plating, frames, aircraft spars, D17 – the main riveted alloy.
High-strength alloys – B95, B96 along with copper and magnesium still contain a significant amount of zinc. Used for highly loaded structures.
Alloys of increased plasticity and corrosion resistance – АВ, АД31, АД33. Helicopters blades, forged and forged parts of complex configuration.
Foundry aluminum alloys
The most common alloys of the system are Al-Si silumin.
Silumin has a combination of high foundry and mechanical properties, low specific gravity. A typical silumin alloy AL2 (AK12) contains 10-13% Si, is subjected to hardening and aging (AK7 (AL9), AK9 (AL4)).