Aluminum alloy has low density but high strength. It is close to or exceeds high-quality steel. It has good plasticity and can be processed into various profiles. It has excellent electrical conductivity, thermal conductivity, and corrosion resistance.Some aluminum alloys can be heat treated to obtain good mechanical properties, physical properties and corrosion resistance. The hard aluminum alloy belongs to the AI-Cu-Mg series and generally contains a small amount of Mn, which can be strengthened by heat treatment. It is characterized by high hardness but poor plasticity.Super-hard aluminum belongs to Al-Cu-Mg-Zn series, which can be strengthened by heat treatment. It is the aluminum alloy with the highest strength at room temperature, but has poor corrosion resistance and rapid softening at high temperatures.Forged aluminum alloys are mainly Al-Zn-Mg-Si series alloys. Although there are many types of added elements, the content is small, so they have excellent thermoplasticity and are suitable for forging.
Pure aluminum has a small density (ρ = 2.7g / cm3), about 1/3 of iron, a low melting point (660 ° C), and aluminum has 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 and plates, and has good corrosion resistance.
However, the strength of pure aluminum is very low, and the σb value in the annealed state is about 8 kgf / mm2, so it is not suitable as a structural material.Through long-term production practice and scientific experiments, people 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 have high strength while maintaining the advantages of pure aluminum and light weight, and the σb values can reach 24-60kgf / mm2, respectively. This makes its "specific strength" (ratio of strength to specific gravity σb / ρ) better than many alloy steels, and becomes an ideal structural material. It is widely used in machinery manufacturing, transportation machinery, power machinery, and aviation industry. , Skin, compressor, etc. are often made of aluminum alloy to reduce their weight. Using aluminum alloy instead of steel plate for welding can reduce the structure weight by more than 50%.