1, metal elements: the influence of copper
Copper is an important alloying element and has a certain solid solution strengthening effect. In addition, CuAl2 precipitated by aging has a remarkable aging strengthening effect. The copper content in aluminum sheets is usually between 2.5% and 5%, and the copper content is best at 4% to 6.8%, so the copper content of most hard aluminum alloys is in this range.
2, metal elements: the influence of silicon
Al-Mg2Si alloy alloy equilibrium phase diagram The maximum solubility of Mg2Si in aluminum in the aluminum-rich sector is 1.85%, and the deceleration is small with the decrease of temperature. In the deformed aluminum alloy, silicon is added to the aluminum plate alone and is limited to the welding material, and the silicon is added to the aluminum. There is also a certain strengthening effect.
3. Metal elements: the influence of magnesium
The strengthening of magnesium to aluminum is remarkable. For every 1% increase in magnesium, the tensile strength is about 34 MPa. If 1% or less of manganese is added, it may supplement the strengthening effect. Therefore, the addition of manganese can reduce the magnesium content, and at the same time reduce the tendency of hot cracking. In addition, manganese can also precipitate the Mg5Al8 compound on average, improving corrosion resistance and welding performance.
4, metal elements: the influence of manganese
The maximum solubility of manganese in the solid solution is 1.82%. The strength of the alloy increases with increasing solubility. When the manganese content is 0.8%, the elongation reaches a maximum. The Al-Mn alloy is a long-term age hardening alloy, that is, it cannot be heat-treated.
5. Metal elements: the influence of zinc
Al-Zn alloy equilibrium phase diagram The solubility of zinc in aluminum is 31.6% at 275, while the solubility at 125 is reduced to 5.6%. Zinc is added to aluminum alone. Under the premise of deformation, the progress of the strength of the aluminum alloy is very limited, and there is a tendency of stress erosion cracking, which limits its application.
6, metal elements: the influence of iron and silicon
In the Al-Cu-Mg-Ni-Fe-based forged aluminum alloy, silicon is added as an alloying element in Al-Mg-Si-based forged aluminum and in Al-Si-based welding rods and aluminum-silicon forged alloys. Among the base metals, silicon and iron are common impurity elements and have a significant effect on the alloy function. They are mainly present 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 ratio of iron to silicon is not good, it will cause cracks in the casting. If the iron content in the cast aluminum is too high, the casting will be brittle.
7, metal elements: the influence of titanium and boron
Titanium is an additive element commonly used in aluminum alloys and is added in the form of an Al-Ti or Al-Ti-B master alloy. Titanium and aluminum form a TiAl2 phase, which becomes a non-spontaneous core during crystallization, and functions to refine the forged structure and the weld bead structure. When the Al-Ti alloy is subjected to a package reaction, the critical content of titanium is about 0.15%, and if boron is present, the deceleration is as small as 0.01%.
8, metal elements: the impact of chromium and antimony
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, and can improve the toughness of the alloy and reduce the sensitivity of stress corrosion cracking. . However, the quenching sensitivity is increased in the meeting place, the anodized film is yellow, the addition amount of chromium in the aluminum alloy is generally not more than 0.35%, and decreases with the increase of the transition element in the alloy, and the addition of 0.015% to the aluminum alloy for extrusion is added. ——0.03% 锶, the β-AlFeSi phase in the ingot is transformed into the Chinese-shaped α-AlFeSi phase, which reduces the average aging time of the ingot by 60%-70%, improves the mechanical properties and plastic workability of the material; improves the surface roughness of the product. Longitude.
For the high-silicon (10% - 13%) deformed aluminum alloy, adding 0.02% - 0.07% lanthanum element can reduce the primary crystal to a minimum, the mechanical function is also improved, and the tensile strength бb is improved from 233 MPa to 236 MPa. The yield strength σ0.2 was increased from 204 MPa to 210 MPa, and the elongation б5 was increased from 9% to 12%. The addition of yttrium to the hypereutectic Al-Si alloy can reduce the size of the primary silicon particles, improve the plastic working function, and smoothly perform hot rolling and cold rolling.