Aluminum grade and characteristics
Classification of aluminum plate grades According to the different metal elements contained in the aluminum plate, the aluminum plate can be roughly divided into 9 categories, that is, it can be divided into 9 series. The following is a step-by-step introduction.
1.1000 series represents 1050 1060 1070 1000 series aluminum plate is also known as pure aluminum plate, among all series, 1000 series belongs to the series with the most aluminum content. The purity can reach more than 99.00%. Because it does not contain other technical elements, the production process is relatively simple and the price is relatively cheap. It is the most commonly used series in conventional industries at present. Most of the current circulation in the market are 1050 and 1060 series. The minimum aluminum content of the 1000 series aluminum plate is determined according to the last two Arabic numerals. For example, the last two Arabic numerals of the 1050 series are 50. According to the international brand naming principle, the aluminum content must reach 99.5% or more to qualify as a product. my country’s aluminum alloy technical standard (gB/T3880-2006) also clearly stipulates that the aluminum content of 1050 should reach 99.5%. In the same way, the aluminum content of 1060 series aluminum plates must reach more than 99.6%.
2.2000 series aluminum plate represents 2A16 (LY16) 2A06 (LY6) 2000 series aluminum plate is characterized by high hardness, among which the copper content is the highest, about 3-5%. The 2000 series aluminum plate belongs to aviation aluminum, which is not commonly used in conventional industries at present. At present, there are fewer manufacturers producing 2000 series aluminum sheets in our country. The quality can not be compared with foreign countries. Currently imported aluminum sheets are mainly provided by South Korean and German manufacturers. With the development of my country’s aerospace industry, the production technology of 2000 series aluminum plates will be further improved.
Three. 3000 series aluminum plate represents 3003 3003 3A21 mainly. It can also be called anti-rust aluminum plate. The production process of 3000 series aluminum plate in my country is relatively excellent. The 3000 series aluminum plate is mainly composed of manganese. The content is between 1.0-1.5. It is a series with better anti-rust function. Routinely used in humid environments such as air conditioners, refrigerators, and undercarriages, the price is higher than 1000. It is a more commonly used alloy series.
Four. The 4000 series aluminum plate is represented by the 4A01 4000 series aluminum plate, which belongs to the series with a high silicon content. Usually the silicon content is between 4.5-6.0%. It belongs to building materials, mechanical parts, forging materials, welding materials; low melting point, good corrosion resistance Product Description: It has the characteristics of heat resistance and wear resistance.
5. The 5000 series aluminum plate belongs to the more commonly used alloy aluminum plate series, the main element is magnesium, and the magnesium content is between 3-5%. It can also be called aluminum-magnesium alloy. The main features are low density, high tensile strength and high elongation. In the same area, the weight of aluminum-magnesium alloy is lower than other series. Therefore, it is often used in aviation, such as aircraft fuel tanks. It is also widely used in conventional industries. The processing technology is continuous casting and rolling, which belongs to the series of hot-rolled aluminum plates, so it can be used for oxidation deep processing. In my country, the 5000 series aluminum plate belongs to one of the more mature aluminum plate series.
6. The 6000 series represents 6061, which mainly contains two elements of magnesium and silicon, so the advantages of the 4000 series and 5000 series are concentrated. 6061 is a cold-processed aluminum forged product, suitable for applications requiring high corrosion resistance and oxidation resistance. Good workability, excellent interface characteristics, easy coating, good processability. Can be used on low pressure weapons and aircraft connectors. General characteristics of 6061: excellent interface characteristics, easy coating, high strength, good workability, and strong corrosion resistance. Typical uses of 6061 aluminum: aircraft parts, camera parts, couplers, marine accessories and hardware, electronic accessories and joints, decorative or various hardware, hinge heads, magnetic heads, brake pistons, hydraulic pistons, electrical accessories, valves and valve parts .
Seven. The 7000 series represents that 7075 mainly contains zinc. It also belongs to the aviation series. It is an aluminum-magnesium-zinc-copper alloy. It is a heat-treatable alloy. It belongs to superhard aluminum alloy and has good wear resistance. The thick 7075 aluminum plate is all ultrasonically detected, which can ensure no blisters and impurities. The high thermal conductivity of the 7075 aluminum plate can shorten the forming time and improve work efficiency. The main feature is that the hardness is high. 7075 is a high-hardness, high-strength aluminum alloy, which is often used in the manufacture of aircraft structures and futures. It requires high-stress structural parts and mold manufacturing with high strength and strong corrosion resistance. Currently basically rely on imports, my country’s production technology needs to be improved.
8. The more commonly used 8000 series is 8011, which belongs to other series. The aluminum plate whose main function is to make bottle caps is also used in radiators, most of which are aluminum foils. Not very commonly used.
Aluminum and its alloys
1. Pure aluminum
Aluminum (aluminum, aluminum) is characterized by a low density of 2.72g/cm3, which is only about 1/3 of the density of iron or copper. Good electrical and thermal conductivity, second only to silver and copper. The chemical properties of aluminum are very active. In the air, the surface of aluminum can combine with oxygen to form a dense Al2O3 protective film to prevent further oxidation of aluminum. Therefore, aluminum has good corrosion resistance in air and water, but aluminum is not resistant to acid, alkali, and salt corrosion.
Aluminum has a face-centered cubic lattice, good plasticity (δ=50%, ψ=80%), and can be processed into wires, plates, strips, pipes and other profiles through cold or hot pressure processing, but the strength is not high, σb=80MPa , After cold working, σb = (150 ~ 250) MPa. Therefore, pure aluminum is mainly used to make wires, cables, radiators, and daily necessities or alloys that require stainless steel, corrosion resistance, and low strength requirements.
Industrial pure aluminum (commercial purity aluminum) is not as pure as chemically pure aluminum, it has more or less impurities (such as Fe, Si, etc.). The more impurities contained in aluminum, the lower its electrical conductivity, thermal conductivity, atmospheric corrosion resistance and plasticity.
The grades of China’s industrial pure aluminum are compiled based on the limits of impurities, such as L1, L2, L3… L is the Chinese pinyin prefix of the word “aluminum”, and the larger the sequence number attached thereto, the lower the purity.
2. Aluminum alloy
The strength of pure aluminum is very low, so it is not suitable for structural materials. In order to improve its strength, the most effective way is to add alloying elements, such as Si, Cu, Mg, Mn, etc., to make aluminum alloy (aerolite). These aluminum alloys have high strength and low density, especially high specific strength (that is, the ratio of strength limit to density) and good thermal conductivity and corrosion resistance.
(1) Classification of aluminum alloys
According to the composition and production process characteristics of aluminum alloys, aluminum alloys can be divided into two types: deformed aluminum alloys and cast aluminum alloys.
It can be seen from the figure that when the alloy with a composition less than D/point can form a single-phase solid solution structure when heated, it has good plasticity and is suitable for pressure processing, so it is called a deformed aluminum alloy. If the composition of the deformed aluminum alloy is less than the F point, the composition of its solid solution does not change with the change of temperature, because it cannot be strengthened by heat treatment, it is called an aluminum alloy that cannot be strengthened by heat treatment; the composition of the alloy between F and D/, its solid solution composition It changes with the change of temperature, so it can be strengthened by heat treatment, so it is called aluminum alloy that can be strengthened by heat treatment. Alloys with a composition greater than D/point have a low melting point eutectic structure, good fluidity, and are suitable for casting. They are called cast aluminum alloys, but they are not suitable for pressure processing.
Deformable aluminum alloys can also be divided into antirust aluminum, duralumin, super duralumin and wrought aluminum according to their main performance characteristics.
Cast aluminum alloys can also be divided into: Al-Si, Al-Cu, Al-Mg, Al-Zn, etc. according to the main alloy elements.
(2) Heat treatment characteristics of aluminum alloy
Aluminum alloy can not only improve its strength by cold deformation work hardening method, but also further improve its strength by heat treatment – “age hardening” method.
The heat treatment mechanism of aluminum alloy is different from that of steel. After quenching, the hardness and strength of the steel increase immediately, while the plasticity decreases. However, the aluminum alloy whose composition is between F and D/ is heated to the α phase region, kept warm, and water-cooled and quenched, and a supersaturated α solid solution can be obtained at room temperature. The strength and hardness cannot be increased immediately, but the plasticity has been significantly improved. This process is called quenching or solution treatment. Since the supersaturated solid solution obtained after quenching is unstable, there is a tendency to precipitate the second phase (strengthening phase). When placed at room temperature for a period of time or heated at low temperature, the atoms have the ability to move in the lattice and gradually transform to a stable state, resulting in a significant increase in strength and hardness and a decrease in plasticity. The phenomenon that the alloy after solution treatment is further strengthened over time is called “age strengthening” or “age hardening”. The aging at room temperature is called natural aging, and the aging under heating is called artificial aging.
(3) Deformed aluminum alloy
1. Anti-rust aluminum alloy
The main alloying elements are Mn and Mg. This kind of alloy is single-phase solid solution after forging and annealing, so it has good corrosion resistance and good plasticity. Such as LF5, LF11, LF21, etc. This type of alloy is mainly used for rolling, welding, or corrosion-resistant structural parts with small loads, such as fuel tanks, conduits, wires, light-load skeletons, and various living appliances.
All kinds of antirust aluminum alloys are aluminum alloys that cannot be strengthened by heat treatment. To increase the strength of the alloy, it can be processed by cold pressure, which can produce work hardening.
2. Hard aluminum alloy
Duraluminium is basically an Al-Cu-Mg alloy and contains a small amount of Mn. All kinds of duraluminium can be aged strengthened, but their corrosion resistance is poor, especially in seawater, so protective duraluminium parts are needed Its exterior is covered with a layer of high-purity aluminum to make aluminum-clad duralumin.
The hard aluminum grades use the Chinese pinyin prefix “LY” of “aluminum hard” and the sequence number, such as LY1 (rivet hard aluminum), LY11 (standard hard aluminum) and LY12 (high-strength hard aluminum).
Duralumin is a structural material with high specific strength, and has been widely used in the aviation industry and instrument manufacturing.
3. Super hard aluminum alloy (SD alloy)
It is Al-Cu-Mg-Zn alloy, which is made of adding Zn on the basis of duralumin. This type of alloy is currently the strongest aluminum alloy with higher specific strength, so it is called super duralumin. The disadvantage is also that the corrosion resistance is very poor, and the artificial aging temperature can be increased or the aluminum can be clad.
The grade of superhard aluminum alloy is indicated by the Chinese pinyin prefix “LC” of “Al Chao” plus the serial number. Such as LC4, LC6, etc., are mostly used to manufacture important components with high stress, such as aircraft girders.
4. Wrought aluminum alloy
It is an Al-Cu-Mg-Si alloy. Although there are many types of alloy elements, the content of each element is small, so it has good thermoplasticity and corrosion resistance, and its strength is comparable to that of duralumin. The strength can be increased after quenching and aging.
The grade of wrought aluminum alloy is indicated by the Chinese pinyin prefix “LD” of “aluminum forging” plus a sequence number, such as LD5, LD7, etc. Due to its good forging performance, it is mainly used for forgings or die forgings that bear heavy loads on aircraft or diesel locomotives.
(4) cast aluminum alloy (cast aluminum alloy)
There are many types of cast aluminum alloys. Among them, aluminum-silicon alloys have good casting properties, sufficient strength, and low density, and are the most widely used, accounting for more than 50% of the total output of cast aluminum alloys. Si (10-13)% Al-Si alloy is the most typical aluminum-silicon alloy, which belongs to the eutectic composition, and is usually called “silicon aluminum alloy”.
The grade of cast aluminum alloy is represented by the Chinese pinyin prefix of “Zhu” + Al + other main element symbols and percentage content. For example, ZAlSi12 represents a cast Al-Si alloy containing 12% Si. The code name of the alloy is represented by the Chinese pinyin prefix “ZL” of “cast aluminum” plus three digits. The first digit indicates the alloy category, and the second and third digits indicate the serial number of the alloy. Example ZL102 represents No. 2 Al-Si cast aluminum alloy.
Cast aluminum alloys are generally used to make parts with light weight, corrosion resistance, complex shapes and certain mechanical properties.