Aluminum alloy is the most widely used non-ferrous metal structural materials in the industry, and has been widely used in aviation, aerospace, automotive, machinery manufacturing, ship aluminum alloy and chemical industry. With the rapid development of science and technology and industrial economy in recent years, the demand for aluminum alloy welded structural parts is increasing, so that the weldability research of aluminum alloy has also been deepened. The wide application of aluminum alloy has promoted the development of aluminum alloy welding technology, and the development of welding technology has expanded the application field of aluminum alloy, so aluminum alloy welding technology is becoming one of the hot spots in research.
The density of pure aluminum is small (ρ=2.7g/cm3), about 1/3 of iron, low melting point (660 °C), aluminum is a face-centered cubic structure, so it has high plasticity (δ: 32~40%, ψ: 70~90%), easy to process, can be made into various profiles, plates. Good corrosion resistance; However, the strength of pure aluminum is very low, and the annealed state σb value is about 8kgf/mm2, so it is not suitable for structural materials. Through long-term production practice and scientific experiments, people gradually strengthen aluminum by adding alloying elements and using heat treatment, which obtains a series of aluminum alloys. The alloy formed by adding certain elements can also have high strength while maintaining the advantages of pure aluminum and light weight, and the σb value can reach 24~60kgf/mm2 respectively. This makes its "specific strength" (the ratio of strength to specific gravity σb/ρ) better than many alloy steels, becoming an ideal structural material, widely used in machinery manufacturing, transportation machinery, power machinery and aviation industry, aircraft fuselage, skin, compressor, etc. are often made of aluminum alloy to reduce their own weight. The welding of aluminum alloy instead of steel plate material can reduce the weight of the structure by more than 50%.
