Aluminum alloy is the most widely used non-ferrous metal structural material in industry and has been widely used in aviation, aerospace, automobile, machinery manufacturing, shipbuilding and chemical industries. With the rapid development of science, technology and industrial economy in recent years, the demand for aluminum alloy welded structural parts is increasing day by day, which has led to in-depth research on the weldability of aluminum alloys. The wide application of aluminum alloys has promoted the development of aluminum alloy welding technology. At the same time, the development of welding technology has expanded the application fields of aluminum alloys. Therefore, the welding technology of aluminum alloys is becoming one of the hot spots of research.
The density of pure aluminum is small (ρ=2.7g/m3), about 1/3 of iron, and the melting point is low (660°C). Aluminum has a face-centered cubic structure, so it has high plasticity (δ: 32~40%, ψ:70~90%), easy to process, and can be made into various profiles and plates. It has good corrosion resistance; however, the strength of pure aluminum is very low, and the σb value in the annealed state is about 8kgf/mm2, so it is not suitable for structural materials. Through long-term production practice and scientific experiments, people have gradually strengthened aluminum by adding alloying elements and using heat treatment, which resulted in a series of aluminum alloys. The alloy formed by adding certain elements can maintain the advantages of pure aluminum such as lightness and high strength, and the σb value can reach 24~60kgf/mm2. This makes its "specific strength" (the ratio of strength to specific gravity σb/ρ) better than many alloy steels, making it an ideal structural material and widely used in machinery manufacturing, transportation machinery, power machinery and the aviation industry, etc., including the fuselage of aircraft. , skins, compressors, etc. are often made of aluminum alloy to reduce their own weight. By using aluminum alloy instead of steel plate material for welding, the structural weight can be reduced by more than 50%.
Aluminum alloy has low density, but relatively high strength, close to or exceeding high-quality steel. It has good plasticity and can be processed into various profiles. It has excellent electrical conductivity, thermal conductivity and corrosion resistance. It is widely used in industry, and its usage is second only to steel. .
Aluminum alloys are divided into two categories: cast aluminum alloys, which are used in the cast state; and deformed aluminum alloys, which can withstand pressure processing. It can be processed into aluminum alloy materials of various shapes and specifications. Mainly used for manufacturing aviation equipment, construction doors and windows, etc.
Aluminum alloys can be divided into deformed aluminum alloys and cast aluminum alloys according to processing methods. Deformed aluminum alloys are divided into non-heat-treatable strengthened aluminum alloys and heat-treatable strengthened aluminum alloys. The non-heat-treatable reinforced type cannot improve mechanical properties through heat treatment and can only be strengthened through cold working deformation. It mainly includes high-purity aluminum, industrial high-purity aluminum, industrial pure aluminum and rust-proof aluminum, etc. Heat-treatable strengthened aluminum alloys can improve their mechanical properties through heat treatment methods such as quenching and aging. They can be divided into hard aluminum, forged aluminum, super-hard aluminum and special aluminum alloys.
Some aluminum alloys can be heat treated to obtain good mechanical properties, physical properties and corrosion resistance.
Cast aluminum alloys can be divided into aluminum-silicon alloys, aluminum-copper alloys, aluminum-magnesium alloys, aluminum-zinc alloys and aluminum rare earth alloys according to their chemical composition. Among them, aluminum-silicon alloys also include simple aluminum-silicon alloys (which cannot be strengthened by heat treatment and have low mechanical properties. Casting Good performance), special aluminum-silicon alloy (can be strengthened by heat treatment, high mechanical properties, good casting performance)
