To the welder about wrought aluminum alloys
- 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.
unalloyed aluminum – 1xxx
- 1xxx series alloys called "Alloy" is very conditional. This high purity versions of commercially pure aluminum. 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.
duralumin – 2xxx
- This is a series thermally hardenable aluminum alloys.
- The main alloying element is copper, from 0,7 to 6,8 %.
- Their tensile strength of from 190 to 430 MPa. 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 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.
Aluminum-manganese alloys – 3xxx
- Aluminum alloys of the series - not heat-hardened to a tensile strength of from 110 to 280 MPa.
- The main alloying element - manganese, from 0,5 to 1,8 %.
- They have moderate strength, good corrosion resistance, good formability and suitable for operation at elevated temperatures. they used to make kitchen utensils.
- They are the main material in 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 – 4xxx
- This series consists of both thermally hardened, and thermally neuprochnyaemyh aluminum alloys.
- Tensile strength – from 170 to 380 MPa.
- Contains 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.
Aluminum-magnesium alloys – 5xxx
- Thermally neuprochnyaemye aluminum alloys in this series have a tensile strength of 125 to 350 MPa.
- Contains magnesium from 0,2 to 6,2 %.
- These alloys have the highest strength among neuprochnyaemyh alloys and thermally well welded.
- Widely used in the form of sheets and plates in 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 It is generally considered to limit the content of magnesium, 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.
Cplavs aluminum-magnesium-silicon – 6xxx
- These thermally hardenable aluminum alloys have a tensile strength of from 125 to 400 MPa.
- Contains small amounts of magnesium and silicon - approx. 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.
High-strength aluminum alloys – 7xxx
- 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, which is welded to the main welding alloys series 5xxx.
Source:
- Welding aluminium / T. Anderson – www.thefabricator.com