Be from Aluminum deep processing
Aluminum alloys show different performance characteristics due to different metal elements. Among the various metal elements, the elements that have great influence on the performance of aluminum alloy are copper (Cu), magnesium (Mg), silicon (Si), iron (Fe), manganese (Mn), nickel (Ni), zinc (Zn) and so on. Because of the different uses of finished aluminum coil, these impurity elements are added in the processing process, and their structures are different from the compounds formed by aluminum because of their different melting points.
Cu
Advantages:
Copper is an important alloy element, which has the effects of solution strengthening and aging strengthening. The strengthening effect is the best when the copper content is 4% to 6.8%, so the copper content of most hard aluminum alloys is in this range. Increasing the copper content can improve the fluidity, tensile strength and hardness of the alloy, improve the mechanical properties and improve the machinability.
Disadvantages:
Reduce corrosion resistance and molding, and increase hot cracking tendency.
Mg
Advantages:
Magnesium can significantly strengthen aluminum. For every 1% increase of magnesium, the tensile strength increases by about 34MPa. If less than 1% manganese is added, the strengthening effect may be supplemented. Therefore, adding manganese can reduce the content of magnesium, and at the same time reduce the tendency of hot cracking. In addition, manganese can make Mg5Al8 compound precipitate evenly, and improve the corrosion resistance and welding function.
Disadvantages:
Mg2Si will make the casting brittle.
Si
Advantages:
Al-Mg2Si alloy system alloy equilibrium phase diagram The maximum solubility of Mg2Si in aluminum in aluminum-rich department is 1.85%, and the deceleration is small with the decrease of temperature. In wrought aluminum alloy, the addition of silicon to aluminum plate alone is limited to welding materials, and the addition of silicon to aluminum also has a certain strengthening effect. The addition of Si can improve the casting properties of the alloy. Silicon and aluminum can form a solid solution, which can improve the high-temperature formability of the alloy, reduce the shrinkage and have no tendency of hot cracking. Improve tensile strength, hardness, machinability and strength at high temperature, and reduce elongation.
Disadvantages:
Crystallized silicon (Si) is prone to hard spots of free silicon, which makes the machinability worse, and the high-silicon aluminum alloy has serious erosion effect on casting crucible.
Fe
Advantages:
The adhesion of aluminum alloy to mold is very strong, especially when the iron content is below 0.6%, that is, it is difficult to demould. When the iron content exceeds 0.6%, the phenomenon of die sticking is greatly reduced.
Disadvantages:
When the iron content in aluminum alloy is too high, iron exists in the alloy in the form of flake or needle-like structures of FeAl3, Fe2Al7 and Al-Si-Fe, forming metal compounds and forming hard spots. This kind of structure will also reduce the mechanical properties, increase the hot cracking, and make the castings brittle. And when the iron (Fe) content exceeds 1.2%, the fluidity of the alloy is reduced, the quality of castings is damaged, and the life of metal components in die casting equipment is shortened.
Mn
Advantages:
The strength of the alloy increases with the increase of solubility. When the manganese content is 0.8%, the elongation reaches the maximum. Manganese (Mn) can prevent the recrystallization process of aluminum alloy, increase the recrystallization temperature, and significantly refine the recrystallized grains. The refinement of recrystallized grains is mainly due to the hindrance of the growth of recrystallized grains by the dispersed particles of MnAl6 compound. Another function of MnAl6 is to dissolve the impurity iron (Fe) to form (Fe, Mn)Al6, which can turn the flake or needle-like structure formed by iron in aluminum alloy into fine crystal structure and reduce the harmful effects of iron.
Disadvantages:
When the manganese content is too high, it will cause segregation. Al-Mn alloy hardened by long and short aging, that is, it cannot be strengthened by heat treatment.
Ni
Advantages:
Tend to increase the tensile strength and hardness, which has a great influence on corrosion resistance.
Disadvantages:
Reduce corrosion resistance and thermal conductivity.
Zn
Advantages:
Adding zinc and magnesium into aluminum to form strengthening phase Mg/Zn2 will obviously strengthen the alloy.
Disadvantages:
When zinc is added into aluminum alone, the strength of aluminum alloy is very limited under the premise of deformation, and there is a tendency of stress corrosion cracking, which limits its application.