Industrial wrought aluminum alloys are divided into seven series. There are eight more - alloys, which do not fall in the first seven series and ninth – Reserve. The difference between lots is different principal alloying elements. The various alloying elements are given various properties of aluminum alloys.
Welding pure aluminum
1xxx series alloys called "Alloy" is very conditional. This high purity versions of commercially pure aluminum. GOST 4784 so he calls them: "aluminum grades". However, iron is often not only the impurity, but also alloying element - it increases the strength of aluminum. The tensile strength of alloys of this series is from 70 to 150 MPa. They are welded, although due to the narrow solidification interval require special welding technology. Their high corrosion resistance makes them suitable for use in the chemical tanks and pipes. Due to their high electrical conductivity is used for the manufacture of bus bars. These aluminum alloys have relatively low strength properties and are therefore rarely used for structural elements. They are often welded welding materials with the same chemical composition or welding aluminum alloys from 4xxx series, depending on the product destination and the conditions of its operation.
welding of duralumin
series 2xxx. This is a series thermally hardenable aluminum alloys. Their tensile strength of from 190 to 430 MPa. They contain copper from 0,7 to 6,8 %. These high-strength alloys are frequently used in aerospace engineering and aircraft. They retain high strength in a wide temperature range.
Most of them are not considered to be welded by arc welding because of their tendency to hot cracking and stress corrosion. However, in this series, there is a specially designed well-arc-welded aluminum alloys 2219 (our D20) and 2519. They are often related welded high-strength alloy welding 2319. Sometimes, depending on the operating conditions of the weld, used for welding aluminum alloys from 4xxx series, containing silicon or silicon in combination with copper.
Welding of aluminum-manganese alloys
series 3hhh. Aluminum alloys of the series - not heat-hardened to a tensile strength of from 110 to 280 MPa. The main alloying element - manganese, from 0,05 to 1,8 %. They have moderate strength, good corrosion resistance, good formability and suitable for operation at elevated temperatures. In the past years we have enjoyed making cookware. Now they are the primary material for the manufacture of heat exchangers for vehicles, chemical plants and power stations. Their modest strength properties make them unsuitable for structural applications. Aluminum alloys 3xxx series weld welding alloys of the series 1xxx, 4xxx and 5xxx, Depending on their chemical composition, conditions of use and operation.
Welding aluminum alloys
series 4XXX. This series consists of both thermally hardened, and thermally neuprochnyaemyh aluminum alloys. Tensile strength – from 170 to 380 MPa. They contain silicon from 0,6 to 21,5 %. Silicon lowers the melting point and increase the fluidity of the material during melting. These properties are quite favorable for them as materials for fusion welding and brazing. Silicon, when it is itself, Aluminum makes thermally neuprochnyaemym, however, magnesium or copper additives make it a thermally hardenable alloy. Usually these thermally hardenable alloys are used for welding only, when welded structure after welding must be subjected to heat treatment.
Welding of aluminum-magnesium alloys
5xxx series. Thermally neuprochnyaemye aluminum alloys in this series have a tensile strength of 125 to 350 MPa. They contain magnesium from 0,2 to 6,2 %. These alloys have the highest strength among neuprochnyaemyh alloys and thermally well welded. They are widely applied in the form of sheets and plates for shipbuilding, transport engineering, in the manufacture of pressure vessels, construction of bridges and buildings. Aluminum alloys with magnesium content of up 2,5 % often successfully welded by welding aluminum alloys of the 5xxx series and 4xxx. Alloy 5052 (alloy AMg2,5 according to GOST 4784) is usually considered to be limiting in magnesium content, when you can weld a welding alloy of the 4xxx series. This is due to reduced mechanical properties of welds occurring due eutectic submelting. Therefore, alloys with high magnesium content is not welded welding alloys from 4xxx series, a series 5xxx alloys with similar chemical composition.
Welding alloys magnesium-aluminum-silicon
series 6hhh. These thermally hardenable aluminum alloys have a tensile strength of from 125 to 400 MPa. They contain small amounts of magnesium and silicon - about 1 % each. 6xxx series alloys are widely used in welded construction structures, mainly in the form of extruded sections. These aluminum alloys are prone to hot-cracking during the solidification of the weld. Therefore, they are not welded without filler wire or welding rod. Welding alloy is mixed in the weld pool with a weldable alloy and prevents hot cracking of the weld. 6xxx alloys welded as a welding alloys 4xxx, and welding 5xxx alloys, depending on the purpose of the welded product and its conditions of use.
Welding high-strength aluminum alloys
series 7hhh. This series It includes thermally hardenable aluminum alloys with a strength of 220 to 610 MPa. The main alloying element is zinc in an amount from 0,8 to 12,0 %. The strongest aluminum alloys belong to this series. 7xxx series alloys are used in aircraft, space technology, sports equipment. As in the 2xxx series, most of the alloys of this series are not considered to be welded by arc welding. However, it also has a well-weldable alloys, as, for example, alloy 7005 (alloy 1915 GOST 4784), which is welded to the main welding alloys series 5xxx.
Source: T. Anderson, www.thefabricator.com