Aluminium alloy is the most widely used in industry of a class of non-ferrous metal structure material, in aviation, aerospace, automotive, machinery manufacturing, shipping and the chemical industry has a large application.

In recent years, with science and technology and industrial economic development, to the aluminum alloy welding structure of the increasing demand, aluminum alloy welding study is then further.

The wide application of aluminum alloy aluminum alloy welding technology promoted the development, at the same time, the welding technology development and expand the application field of aluminum alloy, aluminum alloy welding technology is therefore become one of the hot spot in the research.

The density of pure aluminum small (ρ = 2.7 g/cm3), is about one-third of iron, the low melting point (660 ℃), aluminum is face heart cubic structure, it has high plastic (δ: 32 ~ 40%, ψ: 70 ~ 90%), easy processing, can be made into all profiles, the plank. Corrosion properties is good; But the strength of the pure aluminum is very low, annealing state σ b is about 8 value KGF/was, so is unfavorable for structural materials.

Through the long-term production practice and scientific experiments, people gradually to join alloy element and use heat treatment methods to strengthen thealuminum, it got a series of aluminum alloy. Add certain elements of the formation of the pure aluminum alloy in keeping the advantages of light at the same time also can with high strength, σ b respectively to 24 ~ 60 KGF/was. This makes the "than strength" (strength and the ratio of the proportion of σ b/ρ) is better than a lot of alloy steel, become the ideal structure materials, widely used in mechanical manufacture, transport machinery, mechanical power and aviation industry, the plane's fuselage, efficiency, often in aluminium alloy compressor etc, in order to reduce weight. Using aluminum alloy steel material instead of the welding structure can reduce weight more than 50%.

The low density of aluminum alloy, but strength is higher, close to or more than the high quality steel, plastic and can be processed into various materials, with excellent electrical conductivity, thermal conductivity and resistance to corrosion, widely used in industry, is second only to use steel.

According to the aluminum alloy processing method can be divided into deformation aluminum alloy and aluminum alloy casting two kinds big:

Deformation aluminum alloy can withstand the pressure processing. Can be processed into various form, specifications of the aluminium alloy material. Mainly used to make aviation equipment, building doors and Windows, etc. Aluminium alloy and heat treatment deformation is divided into not enhanced aluminum alloy and aluminum alloy can be enhanced heat treatment. Do not heat treatment enhanced by heat treatment not to increase mechanical properties, can only through the cold deformation to achieve improved, it mainly includes the high purity aluminium, industrial high purity aluminium, aluminium industry and antirust aluminum, etc. Heat treatment can be enhanced by quenching and limitation of aluminum alloy and heat treatment means to improve mechanical properties, it can be divided into hard aluminum, forging aluminum, aluminum and special super hard alloy etc.

According to the chemical composition cast aluminium can be divided into al-si alloy, copper alloy aluminum, aluminum magnesium alloys, aluminum and zinc alloy and aluminum of rare earth alloy, aluminum alloy of silicon and simple al-si alloy (can't heat treatment strengthening, mechanical properties is low, casting performance is good, special silicon aluminium alloy (heat treatment can be strengthened, mechanical properties, high performance good casting), casting aluminum alloy in as-cast use.

Some aluminum alloy can use heat treatment for good mechanical properties, physical properties and corrosion resistance.

2008 Beijing Olympic Games torch "clouds" is the aluminum alloy.