Aluminum is a very popular metal both in construction and in other spheres of human life. However, in its pure form it is used very rarely. Most commonly used are aluminum alloys.
All alloys can be divided into cast and wrought alloys. The first type is made by melting, and pressure is used to make the alloys of the second type. Cast aluminum alloys are often represented by the combination of aluminum with silicon. Such metals are strong, have high corrosion resistance, are well cut. As for deformable alloys, duralumin is known among them, which contains aluminum, magnesium and copper. Wire, profile, sheets, tape are made from this metal. The presented alloy can be processed by any means.
The properties of aluminum alloys can be divided into physical, mechanical and chemical. With regard to physical properties, alloys have almost the same density as aluminum itself. They have high strength, which can compete with titanium and steel. But here it is necessary to take into account that the melting point of the alloys is small (it is about 200 degrees). It is worth noting that aluminum alloys have good thermal conductivity, they conduct electricity remarkably, they weld well and are resistant to corrosion, although these properties are much higher for pure aluminum.
As for the mechanical properties, they become higher with increasing degree of alloying. The presented aluminum alloys are used for the construction of structures of low and medium loading. It is worth noting that the properties of the alloys significantly change after heating to a certain temperature, which determines the use.
Since the alloys must be processed before use, and to create certain structures the elements of the alloys have to be welded, attention should be paid to the fact that the welding of aluminum alloys has certain features. The process has some difficulties:
- alloys are difficult to weld due to the oxide film that appears on the surface of the metal (it often contaminates the seam, which prevents the normal fusion of the edges of the metal);
- the oxide film and the alloy itself have different melting points, and the difference can be significant;
- since the casting expansion of aluminum is quite high, after welding, the metal can seriously deform;
- alloys have high fluidity, therefore, when welding on metal, streams may appear.
For welding alloys, carbon or metal electrodes are mainly used. The process is carried out using direct current of reverse polarity. Before starting work, the surface to be welded must be treated with acetone or gasoline and cleaned with a steel brush. In order for welding to proceed more efficiently, it is necessary to warm the parts to be welded to a certain temperature (200 degrees). To get a good weld after welding, cool it slowly.