To maintain a predetermined chemical composition of the aluminum melt is the most important task in the recycling of aluminum scrap – in the smelting of aluminum scrap. – .. It is necessary to take into account the characteristics of the chemical composition of various types of aluminum alloys, first of all, wrought or cast.
Wrought Aluminum Alloys
As their name implies, wrought aluminum alloys - those alloys, that, Unlike the casting of aluminum alloys, are transformed into the final product by plastic deformation - pressure treatment, namely - pressing (extrusion), forging or rolling. Such alloys for the more 200. Almost all of them are made, at least, on 90 % aluminum, and most of them - even 95 %. Wrought aluminum alloys are divided into eight series (classes, groups), which are based on the selection of the alloying elements. This classification system of deformable aluminum alloys has been developed in the US in the 1950s and is now a generally accepted worldwide.
Alloys 1xxx - almost pure aluminum
These alloys - 1xxx alloys according to the international classification of aluminum or technical domestic standards, for example, GOST 4784-97 - contain 99 % or more of aluminum. High aluminum content provides them with high electrical conductivity and corrosion resistance, but also gives the lowest strength among other aluminum alloys. 1xxx series alloys are used in the electrical industry, as well as a packaging foil and chemical equipment.
Since the required minimum content of aluminum in these alloys are so high, the, generally speaking, very difficult to use scrap for the production of these alloys. As a result,, for the manufacture of 1xxx alloys used only primary aluminum scrap and carefully selected within these alloys. However, waste and scrap alloys 1xxx readily used for the production of aluminum alloys any other series.
Alloys 2xxx: a lot of copper
2xxx alloys - including, famous Durand-duralumin D1 and D16 - contain 1 to 6 % Copper alloy according to. Other alloying elements of these alloys include iron, magnesium,, manganese and silicon. These alloys are one of the most durable aluminum alloy, as well as different good toughness. They are widely used in aircraft, as well as for the production of aluminum fasteners - screws, nuts, rivets. 2xxx series alloys are not particularly resistant to corrosion and usually before commissioning paint them or cause them any protective coatings. Most of the aluminum alloys, which do not belong to the series 2xxx, have a copper content of not more than 0,30 % or even less. For this reason, waste and scrap alloys 2xxx can not be used to produce the majority of other series wrought alloys.
3xxx alloys: manganese and iron
Number of 3xxx alloys is very limited, but they have a fairly widespread. These alloys differ manganese content of up 1,5 %, and usually have 0,7-0,8 % gland. They are easy to work hardening - work hardening - and have a very high corrosion resistance.
Most of these alloys are known for their use in the manufacture of aluminum enclosures beer cans - it alloys 3004 and 3104. Alloys of this series is also widely used for the manufacture of kitchen utensils, automobile radiators, roofing and cladding of building materials, as well as heat exchangers. Limiting due 3xxx aluminum alloys with a high content of manganese and iron, which are often undesirable in other alloys.
4xxx alloys: a lot of silicon
Aluminum alloys 4xxx little and are not as widely used as other aluminum alloys deformed. 4xxx alloys contain up to 13 % silicon, which increases their resistance to wear. Their primary use - forging for aircraft engine cylinders. Moreover, 4xxx alloys are used for welding of other aluminum alloys. The high silicon content of these alloys makes it unsuitable for processing into some aluminum alloys other than casting alloys and alloys themselves deformable 4xxx.
5xxx alloys: a lot of magnesium
5xxx alloys are characterized by high magnesium content - up 6 %. Their advantages - a high corrosion resistance, high strength and good weldability. Therefore 5xxx alloys are very widespread. 5xxx alloys are used in such large products, as elements of bridges and tanks, and such small, like beer can lids (alloy 5182). These alloys are increasingly used in load-bearing elements of car design.
Magnesium is the only alloying element, that it can be quite easily removed from the molten aluminum. As a result, 5xxx alloys more easily recyclable, than most other aluminum alloys. However, the high cost of magnesium dictates, these alloys are melted, if possible, Again in the same alloys 5xxx series.
6xxx alloys: magnesium and silicon
6xxx Aluminum alloys contain up to 1,5 % magnesium and to 1,8 % silicon. The presence of these two elements in these alloys makes them thermally hardening. Quite low total content of alloying elements in these alloys provide their good compressibility for manufacturing profiles by extrusion. These alloys are the most popular in the building in the form of aluminum profiles for windows, doors, facades and other enclosing structures. The most stable alloys of this series are used in the automotive industry, in welded building constructions, as well as a high electrical wires.
Like 4xxx alloy major limitation of their processing into other alloys is rather high content of silicon. Moreover, most structural profiles are insulating plastic insert - thermal bridges, which make them remelting big problem.
7xxx alloys: a lot of zinc
7xxx series alloys are alloyed most of all wrought aluminum alloys. They contain 1,5 to 10 % Zinc alloy according to. These alloys also contain up to 3 % magnesium, and some of them - to 2,6 % copper.
Thermally hardenable 7xxx alloys have the highest strength of industrial aluminum alloys and impressive viscous properties. As 2xxx alloys, these alloys due to their low corrosion resistance or paint usually subjected to protective coating.
The maximum consumption of the alloy is in aircraft, as well as in transport engineering. A high content of zinc and copper makes difficult 7xxx alloys for processing into other alloys, except the 7xxx alloys, and cast aluminum alloys.
8xxx alloys - everything else
Aluminum alloys of this series - all the rest, which were not included in the first seven episodes. Extravagant alloying elements of alloys of this series make them unsuitable for processing into other alloys. The high cost of lithium causes lithium alloys processed only in themselves.