2000 series aluminum classification
Al-Cu-Mg alloy
The main composite numbers of AI-Cu-Mg series alloys are 2A01, 2A02, 2A06, 2A10, 2A11, 2A12, etc. The main additive elements are copper, magnesium and manganese. They have the following effects on the alloy:
When ω(Mg) is 1%~2%, ω(Cu) increases from 1% to 4%, the tensile strength of the alloy in the quenched state is increased from 200MPa to 380MPa; the tensile strength of the alloy in the quenched natural aging state is increased from 300MPa Increase to 480MPa. When ω(Cu) is within 1%~4% and ω(Mg) increases from 0.5% to 2.0%, the tensile strength of the alloy increases; when ω(Mg) continues to increase, the strength of the alloy decreases.
ω(Cu)=4.0% and ω(Mg)=2.0% alloy tensile strength value, ω(Cu)=3%~4% and ω(Mg)=0.5%~1.3% alloy, its quenching natural aging Effect. Experiments indicate that the tensile strength of Al-Cu-Mg ternary alloys with ω(Cu)=4%~6% and ω(Mg)=1%~2% can reach 490~ in the quenched natural aging state. 510MPa.
From the endurance strength test value of Al-Cu-Mg alloy with ω(Mn)=0.6% at 200℃ and 160MPa stress, it can be known that the content of ω(Cu)=3.5%~6% and ω(Mg)=1.2%~2.0 % Alloy, durable strength. At this time, the alloy is located on the pseudo-binary cross section of Al-S (Al, CuMg) or near this area. For alloys far away from the pseudo-binary cross-section, that is, when ω(Mg)<1.2% and ω(Mg)>2.0%, the permanent strength decreases. If ω(Mg) is increased to 3.0% or more, the permanent strength of the alloy will decrease rapidly.
Tests at 250°C and 100MPa stress have also obtained similar laws. The literature points out that alloys with permanent strength at 300°C are located in the α+S phase region to the right of the Al-S binary cross section with higher magnesium content.
The Al-Cu binary alloy with ω(Cu)=3%~5% has very low corrosion resistance in the quenched natural aging state. Adding 0.5% Mg can reduce the potential of α solid solution, which can partially improve the corrosion resistance of the alloy. When ω(Mg)>1.0%, the local corrosion of the alloy increases, and the elongation decreases sharply after corrosion.
For alloys with ω(Cu)>4.0% and ω(Mg)>1.0%, magnesium reduces the solubility of copper in aluminum. The alloy has insoluble CuAl 2 and S phases in the quenched state. The presence of these phases accelerates corrosion . The alloys with ω(Cu)=3%~5% and ω(Mg)=1%~4% are located in the same phase zone and have similar corrosion resistance in the quenched natural aging state. The alloy in the α-S phase region has worse corrosion resistance than the α-CuAl 2 -S region. Intergranular corrosion is the main corrosion tendency of Al-Cu-Mg alloys.
Manganese is added to Al-Cu-Mg alloy mainly to eliminate the harmful effects of iron and improve corrosion resistance. Manganese can slightly increase the room temperature strength of the alloy, but it reduces the plasticity. Manganese can also delay and weaken the artificial aging process of Al-Cu-Mg alloy and improve the heat resistance strength of the alloy. Manganese is also one of the main factors that make the Al-Cu-Mg alloy have an extrusion effect. ω(Mn) is generally less than 1%. If the content is too high, it can form coarse (FeMn)Al 6 brittle compounds and reduce the plasticity of the alloy.
A small amount of trace elements added to Al-Cu-Mg alloy are titanium and zirconium, and the impurities are mainly iron, silicon and zinc. The effects are as follows:
(1) Titanium: The addition of titanium to the alloy can refine the as-cast grains and reduce the tendency to form cracks during casting.
(2) Zirconium: A small amount of zirconium and titanium have similar effects, refine the as-cast grains, reduce the tendency of casting and welding cracks, and improve the plasticity of ingots and welded joints. The addition of zirconium does not affect the strength of manganese-containing alloy cold-formed products, and slightly improves the strength of manganese-free alloy.
(3) Silicon: Al-Cu-Mg alloy with ω (Mg) less than 1.0% and ω (Si) more than 0.5%, which can improve the speed and strength of artificial aging without affecting the natural aging ability. Because silicon and magnesium form the Mg 2 Si phase, it is beneficial to improve the artificial aging effect. However, when ω(Mg) is increased to 1.5%, after quenching natural aging or artificial aging treatment, the strength and heat resistance of the alloy will decrease with the increase of ω(Si). Therefore, ω(Si) should be reduced as much as possible. In addition, the increase in ω (Si) will increase the tendency of 2Al2, 2A06 and other alloys to form cracks and decrease the plasticity during riveting. Therefore, the ω (Si) in the alloy is generally limited to 0.5% or less. For alloys that require high plasticity, ω (Si) should be lower.
(4) Iron: Iron and aluminum form FeAl 3 compounds. Iron will dissolve into the compounds formed by copper, manganese, silicon and other elements. These coarse compounds that do not dissolve in solid solution will reduce the plasticity of the alloy and cause the alloy to be deformed. It is easy to crack, and the strengthening effect is obviously reduced. A small amount of iron (less than 0.25%) has little effect on the mechanical properties of the alloy, which can improve the tendency of crack formation during casting and welding, but reduce the natural aging speed. In order to obtain high plasticity materials, the iron and silicon content in the alloy should be as low as possible.
(5) Zinc: A small amount of zinc (ω(Zn)=0.1%~0.5%) has little effect on the mechanical properties of Al-Cu-Mg alloy at room temperature, but it reduces the heat resistance of the alloy. The ω (Zn) in the alloy should be limited to less than 0.3%.
Al-Cu-Mg-Fe-Ni alloy
The main combination numbers of Al-Cu-Mg-Fe-Ni series alloys are 2A70, 2A80, 2A90, etc. Each alloy element has the following functions:
(1) Copper and magnesium: The influence of copper and magnesium content on the room temperature strength and heat resistance of the above alloy is similar to that of the Al-Cu-Mg alloy. Since the content of copper and magnesium in this series of alloys is lower than that of Al-Cu-Mg alloys, the alloys are located in the α+S (Al 2 CuMg) two-phase region, so the alloys have higher room temperature strength and good heat resistance; in addition, When the copper content is low, the low-concentration solid solution has a low tendency to decompose, which is beneficial to the heat resistance of the alloy.
(2) Nickel: Nickel and copper in the alloy can form an insoluble ternary compound. When the nickel content is low (AlCuNi), when the nickel content is high, Al 3 (CuNi) 2 is formed. Therefore, the presence of nickel can reduce the copper in the solid solution. The measurement results of the lattice constant of the quenched state also proved the depletion of copper solute atoms in the alloy solid solution. When the iron content is very low, increasing the nickel content can reduce the hardness of the alloy and reduce the strengthening effect of the alloy.
(3) Iron: Like nickel, iron can also reduce the concentration of copper in solid solution. When the nickel content is very low, the hardness of the alloy initially decreases with the increase of the iron content, but when the iron content reaches a certain value, it starts to increase.
When iron and nickel are added to AlCu 2.2 Mg 1.65 alloy at the same time, the characteristics of hardness changes under quenching natural aging, quenching artificial aging, quenching and annealing are similar, and a value appears in the parts with similar contents of nickel and iron. Here, the lattice constant in the quenched state appears to be a minimum.
When the iron content in the alloy is greater than the nickel content, the Al 7 Cu 2 Fe phase will appear. When the nickel content in the alloy is greater than the iron content, the AlCuNi phase will appear. The appearance of the copper-containing ternary phase reduces the concentration of copper in the solid solution. Only when the iron and nickel contents are equal, all Al 9 FeNi phases are formed. In this case, because there is no excess iron or nickel to form an insoluble copper-containing phase, the copper in the alloy not only forms the S(Al 2 CuMg) phase, but also increases the concentration of copper in the solid solution. It is beneficial to improve the strength of the alloy and its heat resistance.
The content of iron and nickel can affect the heat resistance of the alloy. The Al 9 FeNi phase is a hard and brittle compound with very low solubility in Al. After forging and heat treatment, when they are dispersed in the structure, they can significantly improve the heat resistance of the alloy. For example, in AlCu 2.2 Mg 1.65 alloy, ω(Ni)=1.0%, adding ω(Fe)=0.7%~0.9% alloy endurance strength value.
(4) Silicon: Adding ω(Si)=0.5%~1.2% to 2A80 alloy can increase the room temperature strength of the alloy, but reduce the heat resistance of the alloy.
(5) Titanium: Adding ω(Ti)=0.02%~0.1% to 2A70 alloy can refine the as-cast grains and improve the forging process performance, which is beneficial to heat resistance, but has little effect on room temperature performance.
Al-Cu-Mn alloy
The main combination numbers of Al-Cu-Mn series alloys are 2A16, 2A17, etc. The main alloying elements have the following functions:
(1) Copper: At room temperature and high temperature, the strength of the alloy increases as the copper content increases. When ω (Cu) reaches 5.0%, the alloy strength is close to the value. In addition, copper can improve the welding performance of the alloy.
(2) Manganese: Manganese is the main element to improve heat-resistant alloys. It can increase the activation energy of atoms in solid solution, reduce the diffusion coefficient of solute atoms and the decomposition rate of solid solution. When the solid solution is decomposed, the formation and growth of the precipitated T phase (Al 20 Cu 2 Mn 3) is also very slow, so the alloy has stable performance when heated for a long time at a certain high temperature. Adding appropriate manganese (ω(Mn)=0.6%~0.8%) can improve the room temperature strength and endurance strength of the alloy in the quenched and natural aging state. However, if the manganese content is too high, the T phase will increase, which will increase the interface, accelerate the diffusion effect, and reduce the heat resistance of the alloy. In addition, manganese can also reduce the tendency to crack during alloy welding.
The trace elements added to the Al-Cu-Mn alloy are magnesium, titanium and zirconium, while the main impurity elements are iron, silicon, zinc, etc. The effects are as follows:
(1) Magnesium: When the content of copper and manganese in the 2Al6 alloy is unchanged, add ω(Mg)=0.25%~0.45% to form a 2A17 alloy. Magnesium can increase the room temperature strength of the alloy and improve the heat resistance strength below 150~225℃. However, when the temperature rises again, the strength of the alloy decreases significantly. However, the addition of magnesium can deteriorate the welding performance of the alloy, so in the heat-resistant weldable 2A16 alloy, the impurity ω (Mg) ≤ 0.05%.
(2) Titanium: Titanium can refine the as-cast grains, increase the recrystallization temperature of the alloy, reduce the decomposition tendency of supersaturated solid solution, and stabilize the structure of the alloy at high temperatures. However, when ω(Ti)>0.3%, the formation of coarse needle-like crystal TiAl 3 compounds will reduce the heat resistance of the alloy. The ω(Ti) of the alloy is specified as 0.1%~0.2%.
(3) Zirconium: when ω(Zr)=0.1%~0.25% is added to 2219 alloy, the grains can be refined, and the recrystallization temperature of the alloy and the stability of solid solution can be improved, thereby improving the heat resistance of the alloy and improving The weldability of the alloy and the ductility of the weld. However, when ω(Zr) is high, more brittle compound ZrAl 3 can be produced.
(4) Iron: When ω(Fe)>0.45% in the iron alloy, the insoluble phase Al7Cu2Fe is formed, which can reduce the mechanical properties of the alloy in the quenched aging state and the endurance strength at 300℃. So limit ω(Fe)<0.3%.
(5) Silicon: A small amount of silicon (ω(Si)≤0.4%) has no obvious effect on the room temperature mechanical properties, but it reduces the endurance strength at 300℃; when ω(Si)>0.4%, it also reduces the room temperature mechanical properties. Therefore, limit ω(Si)<0.3%.
(6) Zinc: A small amount of zinc (ω(Zn)=0.3%) has no effect on the room temperature performance of the alloy, but it can accelerate the diffusion rate of copper in aluminum and reduce the permanent strength of the alloy at 300℃, so it is limited to ω(Zn)< 0.1%.