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The eight elements that affect the properties of aluminum alloys are: vanadium, calcium, lead, tin, antimony, bismuth, tellurium, and sodium, due to differences in the use of finished aluminum coils. Because the melting point is different, and the structure is different from that of aluminum, the effect on the performance of the aluminum alloy is not the same.
1, metal elements: the impact of copper
Copper is an important alloying element and has a certain solid solution strengthening effect. In addition, CuAl2 precipitated during ageing has a significant age hardening effect. The content of copper in aluminum plates is usually between 2.5% and 5%, and the copper content is between 4% and 6.8%. Therefore, the copper content of most hard aluminum alloys is within this range.
2, metal elements: the impact of silicon
Balanced phase diagram of Al-Mg2Si alloys The maximum solubility of Al-Mg2Si alloys in aluminum is 1.85%, and its deceleration with temperature decreases. In deformed aluminum alloys, silicon alone is added to the aluminum plate and is limited to the welding material. Silicon is added to aluminum. It also has a certain strengthening effect.
3, metal elements: the impact of magnesium
The strengthening of aluminum by magnesium is significant. With every 1% increase in magnesium, the tensile strength increases by approximately 34MPa. If 1% or less of manganese is added, it may increase the strengthening effect. Therefore, after adding manganese, magnesium content can be reduced, and hot cracking tendency can be reduced. In addition, manganese can also cause average precipitation of Mg5Al8 compound and improve corrosion resistance and welding performance.
4, metal elements: the impact of manganese
The maximum solubility of manganese in solid solution is 1.82%. The alloy strength increases with increasing solubility, and the elongation reaches a maximum when the manganese content is 0.8%. Al-Mn alloys are alloys of short and hard age hardening, ie they are not heat-treatable.
5, metal elements: the influence of zinc
The equilibrium phase diagram of Al-Zn alloys in the aluminum-rich sector 275 shows a solubility of zinc in aluminum of 31.6%, while at 125 the solubility drops to 5.6%. When zinc is added to aluminum alone, the strength of the aluminum alloy under the premise of deformation is very limited. At the same time, there is a stress erosion cracking and tendency, which limits its application.
6, metal elements: the impact of iron and silicon
Iron in Al-Cu-Mg-Ni-Fe wrought aluminum alloys, silicon is added as an alloying element in Al-Mg-Si series wrought aluminum and in Al-Si based electrodes and aluminum-silicon wrought alloys. In the base aluminum alloy, silicon and iron are common impurity elements, which have a significant effect on the alloy performance. They mainly exist as FeCl3 and free silicon. When silicon is larger than iron, a β-FeSiAl3 (or Fe2Si2Al9) phase is formed, and when iron is larger than silicon, α-Fe2SiAl8 (or Fe3Si2Al12) is formed. When the proportion of iron and silicon is not appropriate, cracks may be generated in the casting. When the iron content in the cast aluminum is too high, the casting may be brittle.
7, metal elements: the impact of titanium and boron
Titanium is a commonly used additive element in aluminum alloys and is added in the form of Al-Ti or Al-Ti-B master alloys. Titanium forms a TiAl2 phase with aluminum and becomes a non-spontaneous core at the time of crystallization, and functions to refine the forged structure and the weld structure. The critical content of titanium is about 0.15% when the Al-Ti-based alloy generates a package reaction, and the deceleration is as small as 0.01% if boron is present.
8, metal elements: the impact of chromium and cerium
Chromium forms intermetallic compounds such as (CrFe)Al7 and (CrMn)Al12 in the aluminum plate, hinders the nucleation and growth process of recrystallization, has a certain strengthening effect on the alloy, can also improve the toughness of the alloy and reduce the stress corrosion cracking sensitivity . However, the sensitivity of quenching is increased at the venue to make the anodized film yellow, and the addition of chromium in the aluminum alloy is generally not more than 0.35%, and decreases with the increase of the transition elements in the alloy, and 0.015% of the aluminum alloy for extrusion is added to the crucible. ~0.03% 锶, the β-AlFeSi phase in the ingot transforms into the Chinese character α-AlFeSi phase, reduces the average ingot time by 60% to 70%, improves the mechanical properties and plasticity of the material, and improves the surface roughness of the product. . For the high-silicon (10%~13%) deformed aluminum alloys, the addition of 0.02% to 0.07% niobium elements can reduce the primary crystals to the minimum and the mechanical properties also improve significantly. The tensile strength бb increases from 233 MPa to 236 MPa, and the yield strength increases. Б0.2 increased from 204 MPa to 210 MPa, and elongation б5 increased from 9% to 12%. Adding niobium to the hypereutectic Al-Si alloy can reduce the size of the primary crystal silicon particles, improve the plastic processing ability, and can be smoothly hot-rolled and cold-rolled.