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Location:HOME>News>Industry news>Aluminum alloy materials in building Windows and doors, curtain wall application present situation and development prospects

Aluminum alloy materials in building Windows and doors, curtain wall application present situation and development prospects

2020-08-10

Quality of aluminum profiles for doors, windows and curtain walls

GB / t3190-2008 chemical composition of wrought aluminum and aluminum alloy specifies the chemical composition of wrought aluminum and aluminum alloy.

The chemical composition of wrought aluminum and aluminum alloy shall meet the requirements of Table 1.

Aluminum alloy building profile is the main material of aluminum alloy glass curtain wall. At present, 30 forged aluminum (6061) and 31 forged aluminum (6060, 6061, 6063, 6063a) are extruded at high temperature, rapidly cooled and artificially aged (T5) [or solution heat treated (T6)] state. The profiles are anodized (colored), or electrophoretic painted, powder sprayed, fluorocarbon and sprayed.

GB / t5337-2000 specifies the quality of aluminum alloy building profiles. 


1. Chemical composition of aluminum profiles for doors, windows and curtain walls

In order to obtain good extrusion performance, high quality surface treatment performance, suitable mechanical properties, satisfactory surface quality and appearance decoration effect, the chemical composition of the alloy must be strictly controlled.

a) Properties of 6060 aluminum material: tensile strength σ B (MPA): ≥ 470 conditional yield strength σ 0.2 (MPA): ≥ 420 elongation δ 5 (%): ≥ 6

Product features: 1. High strength heat treatment alloy. 2. Good mechanical properties. 3. Good usability. 4. Easy to process and good wear resistance. 5. Good corrosion resistance and oxidation resistance. Main applications: Aviation fixtures, trucks, tower buildings, ships, pipelines and other applications that require strength, weldability and corrosion resistance. Such as: aircraft parts, camera lenses, couplers, ship accessories and hardware, electronic accessories and joints, decorative or various hardware, hinge head, magnetic head, brake piston, hydraulic piston, electrical accessories, valves and valve parts.

b) 6063 alloy has a wide range of chemical elements. Due to the different roles of each element in the alloy, it is necessary to consider the content of each element in the alloy and the collocation of their interrelations in order to obtain ideal properties and better economic benefits.

The main alloying elements are magnesium and silicon, and the main strengthening phase is Mg2Si. In order to ensure that the total amount of Mg2Si in the alloy is not less than 0.75%, and Mg2Si is fully dissolved, the mechanical properties of the alloy can fully meet the requirements of GB / T5237-2000 standard. The solubility of Mg2Si in the aluminum matrix is related to the content of magnesium in the alloy. The mass ratio of magnesium and silicon in Mg2Si is 1.73:1. If Mg2 / Si > 1.73, the excess magnesium will significantly reduce the solubility of Mg2Si in solid aluminum and weaken the strengthening effect of Mg2Si; if mg / s < 1.73, silicon excess has little effect on the solubility of Mg2Si, and it will not weaken the strengthening effect of Mg2Si.

Iron is the main element, which has the greatest impact on the quality of oxidation and coloring. With the increase of iron, the gloss of anodic oxide film is dark, the transparency (the entry "transparency" is provided by Encyclopedia of the industry) is weakened, and the surface brightness of aluminum profile is significantly reduced, which affects the beauty. The profile with high iron content is not suitable for oxidation coloring.

In addition, the compound formed by iron and silicon has strong heat shrinkability, which makes the ingot easy to crack, especially the brittleness of Fe is greater. When Fe > Si, peritectic reaction with higher melting point is produced, which increases the lower temperature limit of brittle zone and reduces the hot cracking tendency. Therefore, it is necessary to control the content and relationship of Mg, Si and Fe, so as to ensure that enough Mg2Si strengthening phase can be formed in the alloy, and a certain amount of excess silicon can be ensured, and the excess amount is less than the iron content in the alloy, and the iron content in the alloy can not affect the quality of oxidation coloring. In this way, the alloy not only has a certain strength, but also reduces the tendency to produce cracks. At the same time, the quality of oxidation coloring will not be reduced.

Although the effect of other elements on the properties of aluminum profile is relatively small, it can not be ignored. When the content of other elements except copper exceeds the specified value, the surface quality of aluminum profiles will be affected in varying degrees.

Although copper has a certain effect on improving the strength of the alloy, it has an adverse effect on the corrosion resistance. Manganese and chromium can improve the corrosion resistance of the alloy The results show that manganese can also improve the strength of the alloy, while chromium can inhibit the folding of Mg2Si phase at the grain boundary, which can delay the natural aging process and improve the strength after artificial aging. However, when the content of manganese and chromium is high, the color of oxide film on aluminum profile will turn yellow and the coloring effect is poor. Titanium can refine grains, reduce hot cracking tendency and increase elongation of aluminum alloy. However, when the content of titanium exceeds 0.10%, the coloring quality of aluminum profiles will be greatly affected. The content of these trace elements should be controlled below 0.10%, so as not to affect the properties of aluminum profiles.


2. Tensile test of aluminum alloy profiles

For the tensile test of LD31 aluminum alloy profile, its specimen and equipment are the same as that of steel. The process is roughly the same.

(1) . elastic stage. Before point a, the stress and stress become proportional, that is, σ = e ε, from point 0 to C, the aluminum profile is in the elastic stage; there is no residual deformation after unloading, and the elastic limit of stress corresponding to C is about 98.07 MPa, and ε is about 0.15%.

(2) . yield stage. LD31 aluminum profile has no obvious flow amplitude. In practice, the stress corresponding to plastic deformation when the linear strain ε = 0.2% is taken as the conditional yield limit, which is expressed as σ 0.2. The yield strength in national standard gb5237 aluminum alloy building profiles is expressed by "specified non proportional elongation stress σ P 0.2". σ P 0.2 refers to the tensile stress value corresponding to the non proportional elongation of the gauge length part of the sample in the tensile state, when the non proportional elongation of the gauge length reaches 0.2% of the original gauge length, and the yield strength is 0.2 value determined by the original graph solution. In gb5237 standard, σ r0.2 (specified residual elongation stress) is chosen as the yield strength because the two values of σ P0.2 and σ r0.2 are similar (according to Hooke's law, unloading law and practice). Therefore, the yield strength can be expressed by any one of them. However, the determination method of σ P 0.2 is simple and does not need to be unloaded for many times. Both international standards and American standards adopt σ P 0.2 to represent yield strength. Therefore, in order to conform to ISO standards, considering rationality and operability, gb5237 standard selects σ P 0.2 as yield strength. The "specified non proportional elongation stress" σ P 0.2 is set as 110 MPa.

 

3. Classification of aluminum rods:

According to the different metal elements contained in aluminum rods, aluminum rods can be divided into eight categories, that is, they can be divided into nine series

1. The 1000 series aluminum rods represent 1050, 1060, and 1100 series. Of all the series, the 1000 series has the most aluminum content. The purity can reach 99.00%. Because there are no 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. Most of the 1050 and 1060 series are in circulation on the market. The minimum aluminum content of 1000 series aluminum plate is determined according to the last two Arabic numerals. For example, the last two Arabic numerals of 1050 series are 50. According to the international brand naming principle, the aluminum content must reach 99.5%, and the top is the qualified product. China's aluminum alloy technical standard (GB / t3880-2006) also clearly stipulates that the aluminum content of 1050 is 99.5%. Similarly, the aluminum content of 1060 series aluminum plate must reach more than 99.6%.

2. 2000 series aluminum rods represent 2A16 (Ly16) and 2A02 (LY6). 2000 series aluminum plate is characterized by high hardness, among which the copper original content is the highest, about 3-5%. 2000 series aluminum rods are aviation aluminum materials, which are not often used in conventional industry.

2024 is a typical duralumin alloy in the Al Cu mg system. It is a heat treatable alloy with high strength, easy machining, easy cutting and general corrosion resistance. After heat treatment (T3, T4, t351), the mechanical properties of 2024 aluminum bar are significantly improved. Its T3 state parameters are as follows: tensile strength 470mpa, 0.2% yield strength 325mpa, elongation: 10%, fatigue strength 105Mpa, hardness 120hb.

The main application of 2024 aluminum rod: aircraft structure, rivet, truck hub, propeller assembly and other structural parts.

3. 3000 series aluminum rods represent 3003 and 3A21. The production process of 3000 series aluminum plate in China is excellent. 3000 series aluminum rods are mainly composed of manganese. The content is between 1.0-1.5, which is a series with good antirust function.

4. The 4000 series aluminum rod represents the 4a01, and the 4000 series aluminum plate belongs to the series with high silicon content. Generally, the silicon content ranges from 4.5% to 6.0%. It belongs to building materials, mechanical parts, forging materials, welding materials; low melting point, good corrosion resistance, product description: heat resistance, wear resistance

5. 5000 series aluminum bars represent 5052, 5005, 5083, 5A05 series. 5000 series aluminum rods belong to the more commonly used alloy aluminum plate series, the main element is magnesium, the magnesium content is between 3-5%. It can also be called aluminum magnesium alloy. Its main characteristics are low density, high tensile strength and high elongation. In the same area, the weight of Al Mg alloy is lower than other series, and it is widely used in conventional industry. In China, 5000 series aluminum plate is one of the more mature aluminum plate series.

6. The 6000 series aluminum rods represent 6060, 6061 and 6063, mainly containing magnesium and silicon. Therefore, the advantages of 4000 series and 5000 series are concentrated. 6061 is a cold-treated aluminum forging product, which is suitable for applications with high requirements for corrosion resistance and oxidation resistance. Good usability, easy coating and good processability.

 7. 7000 series aluminum rods represent 7075, mainly containing zinc. It also belongs to Aviation series. It is al mg Zn Cu alloy, which can be heat treated. It belongs to super hard aluminum alloy. It has good wear resistance. It basically depends on import. The production process in China needs to be improved.

8. 8011 is more commonly used for 8000 Series aluminum rods, belonging to other series, and most of them are used for aluminum foil, which is not commonly used in the production of aluminum rods.


4. Strengthening treatment of aluminum alloy:

The main strengthening methods of aluminum alloy are as follows

1) Deformation strengthening (work hardening (the entry "hardening" is provided by the industry Encyclopedia)): cold pressing is applied to the antirust aluminum alloy which cannot be strengthened by heat treatment, resulting in work hardening and strengthening.

2) Modification (refining and strengthening): suitable for casting aluminum alloy.

3) Solution strengthening: for aluminum alloy, if Cu, Mg, Zn, Si, Mn are added, the limited solid solution can be formed.


5. The molding method of building aluminum materials is as follows

High specific strength (equivalent to high-strength structural alloy steel); corrosion resistance, surface treatment, beautiful and durable (less anti-corrosion workload and low cost in the construction life cycle, which does not affect the normal production and operation, can be used in high humidity, acid rain or coastal areas; wear resistance, fatigue resistance, can be used repeatedly; It has good water tightness (the entry "water tightness" is provided by the industry Encyclopedia), air tightness and water leakage resistance; the recovery rate is more than 90%, and the regeneration energy consumption is low, the cost is low, and it can be recycled repeatedly; it has good sound insulation, sound absorption and water leakage proof effect; The space structure has strong sense of Modernity: aluminum alloy space structure is light, with less foundation investment, which is convenient for loading and unloading and construction, especially for the design, manufacture and construction of high-rise buildings and modern large-span and thin shell structures; Good plasticity, easy to form, can be processed into various shapes of special large-scale hollow and solid profiles, pipes, bars and forging materials, to meet the needs of various styles of building structures, so that the form of building components is more reasonable; aluminum alloy structure has light weight, does not need large-scale heavy machinery configuration, transportation and installation is extremely light, which can greatly shorten the construction period and improve the economic benefits of the owner; The fully assembled construction meets the standards of modularization and building industrialization, and the construction site has no noise, no dust, no pollution to water and gas, which is a typical green material and green construction. Under the same span, the structural section is greatly reduced (about 1 / 8 section of steel structure), which can increase the building area by about 6%, reduce the space waste by about 10%, and save land and energy; Aluminum alloy material can be recycled, the recovery rate is more than 90%, and the energy consumption and cost of recovery are very low, and the recycling rate is high, so it is a typical renewable recycling environmental protection material; Easy transportation, convenient construction and loading and unloading, low maintenance costs, is the most ideal lightweight materials, and lightweight is an important way to achieve "green building" - low carbon, energy saving, environmental protection, safety, therefore, replacing wood with aluminum and steel with aluminum is becoming an important trend of "green building".


6. Advantages of aluminum alloy materials:

1) Light weight;

2) High strength;

3) It is easy to process;

4) Beautiful, suitable for all kinds of surface treatment;

5) Aluminum and aluminum alloys also have the advantages of corrosion resistance, good thermal conductivity and conductivity, and good drug resistance.

6) It can be recycled and reused, which can save energy consumption.

7) Aluminum in building structure and transportation, flexibility, lightweight, energy saving, high speed is one of the best materials for comprehensive selection.

8) With its excellent ductility and a variety of surface treatments, aluminum alloy materials provide the greatest design freedom for architects to design avant-garde buildings in the future - and have high ecological value. The U value of modern aluminum alloy curtain wall unit is low, which makes great contribution to the positive energy output of buildings. The thickness of the material is optimized in the manufacturing process to ensure the low consumption of raw materials. Mechanical durability and anti-corrosion extend the service life of the system and achieve the sustainability of the building to a great extent. Aluminum alloy is completely harmless to the body. A single extraction can be recycled infinitely and retain the original texture in the process. Even debris can be recovered.


7. Development direction of aluminum alloy materials for construction:

Aluminum alloy structural extrusion materials have been widely used in aerospace, transportation, automobile, power and energy, electronic and electrical appliances, electromechanical manufacturing and other aspects. However, its application in construction engineering is only in recent decades. As a structural material for buildings and bridges, aluminum alloy was first used in Italy, Spain, Germany, France, the United States and other industrial developed countries, and then it was popular in Japan, Canada and Britain. At present, the main industrial developed countries in the world replace wood with aluminum and steel with aluminum. Aluminum alloy materials are widely used as green building formwork, scaffolding and other construction machinery materials and engineering structure materials. Due to the poor foundation and weak economic strength (the cost of aluminum is much higher than that of steel), China started late. However, in recent years, due to the strengthening of China's economic strength, China has become a big country in aluminum industry. In addition, it is in the climax of industrialization and urbanization, as well as the popularization of green concept, which greatly promotes the process of replacing wood and steel with aluminum in green building projects. At present, green building aluminum alloy structural materials have been widely used in important buildings in many big cities in China.

1. The characteristics and technical requirements of aluminum alloy structural extrusion materials are summarized as follows:

(1) There are many kinds of products, wide range of specifications, large outline size and sectional area, complex shape, great difference in wall thickness and difficulty coefficient. Most of them are special-shaped hollow profiles, solid profiles with large width thickness ratio, semi hollow profiles with large tongue ratio, and special-shaped pipes and bars.

(2) In order to improve the overall strength and stiffness of buildings, and facilitate the design of modern large-span and thin shell structures, integral composite structural profiles are often used, that is, a large-scale overall structural profile is composed of many small and medium-sized profiles with different shapes. Some of them have a width of more than 600mm, a sectional area of more than 400cm2, a wall thickness difference of more than 20mm, and a tongue ratio of more than 8 The press can only be formed by designing and manufacturing dies with special structure, which is difficult in technology and mass production.

(3) Materials require high strength, rigidity and excellent comprehensive properties, so it is necessary to select alloys and states with various properties. Some of them are 6xxx and 5xxx alloys (such as 6005t6, 6061T6, 6082T6, 5083h112, 5052h112, etc.) which can be welded, cold formed and corrosion-resistant, but the strength must be greater than 300mpa. Therefore, the alloy composition should be adjusted or new alloys should be developed; The other part requires high strength, high toughness alloys (such as 2024t4, 7075 T6, 5a06h112, etc.) with weldability and cold forming properties, so the alloy composition should also be optimized. In addition, in order to ensure the excellent comprehensive performance of structural materials, it is necessary to optimize the casting, extrusion, heat treatment and other processes, design and manufacture of special structure tools and dies, etc., which have high technical content, difficult production, and difficult to improve the yield and efficiency of production.

(4) In order to facilitate the transportation, construction, maintenance and loading and unloading, the dimensional tolerance and geometric tolerance of the product are required to reach the level of high-precision or ultra-high-precision level, which puts forward high requirements for die quality and precision quenching process.

(5) It requires industrialization and mass production, so it puts forward high requirements for equipment, ingot quality, die technology and quality, extrusion and heat treatment process, especially for die structure and service life, which is more than 2 times longer than that of general die, which is very difficult for large special profile die.

  

2. The wide application of extruded aluminum alloy for building and the great significance of its industrial production

(1) Aluminum alloy is the most ideal green building structural material in the world. Its industrialization and wide application are of great significance to promote the development of green building industry, promote the process of urbanization and industrialization in China, and then promote the rapid and sustainable development of national economy and the progress of social civilization. At the same time, it will promote the application of aluminum alloy materials and accelerate the development of aluminum alloy processing industry and technology.

(2) Replacing wood with aluminum in building structure makes aluminum alloy become a real "green building" material, because replacing wood with aluminum can greatly reduce deforestation and protect the green earth and low carbon of the earth. Compared with wood structure, aluminum structure has high strength and rigidity, reduces structural section, increases building area, and saves land and energy; it has good water resistance, waterproof, water tightness and air tightness, and prevents water leakage; it has good corrosion resistance, surface treatment, beautiful and durable; Transportation, construction, maintenance and loading and unloading are convenient, low cost, especially suitable for high-rise and large-span thin shell structure buildings; the recovery rate is more than 90%, the recycling cost and energy consumption are low, and the wood service life is short, so it can only be recycled as garbage. Therefore, aluminum alloy structural material is a kind of real low-carbon, green and recyclable building material.

(3) In building structures, especially in modern high-rise civil buildings and large-scale public buildings with large-span and thin shell structures, aluminum alloy structure has obvious advantages over steel structure

(1) The density is small. The density of aluminum alloy is only 1 / 3 of that of steel, but its specific strength and stiffness are higher than that of steel. In high-rise, long-span and thin shell structures, the weight of aluminum alloy space structure is much lighter than that of steel structure, so the foundation investment of structure is much less. (2) Generally, the B of medium strength aluminum alloy material can reach more than 300 MPa, equivalent to Q235 steel, and the B of 7075t6 ultra-high strength aluminum alloy can reach 700 MPa, which can be compared with high-strength alloy steel and surpass high-strength steel Q345. However, the density of aluminum alloy is small, and the space structure weight of aluminum alloy material is light. Therefore, the specific strength of equal weight structure is higher.

(3) It can be made into precision structural parts of various shapes and specifications. Compared with iron and steel, aluminum alloy has good plasticity and formability. It can be processed into various specifications and shapes of precision hollow and solid constant cross-section and variable cross-section sections, pipes, bars, plates, forgings and die forgings by various pressure processing methods (extrusion, rolling, forging and stamping, etc.) under cold and hot conditions In addition, it can make the section form of the component more reasonable. It can meet the requirements of any building structure without precision machining. This is not achieved by hot rolling, cold rolling, extrusion or welding of steel.

(4) Convenient transportation and installation on site. Because the self weight of aluminum alloy structure is very light, there is no need for large-scale heavy machinery on site, and the transportation and installation is extremely light, so the construction period on site can be greatly shortened and the cost is greatly reduced.

(5) Corrosion resistance, surface treatment, beautiful and durable. Compared with steel structure, one of the main advantages of aluminum alloy structure is corrosion resistance and durability. The anti-corrosion workload in building life is less, and the maintenance cost is low. At the same time, the normal production, operation and use will not be affected by the anti-corrosion maintenance. Green buildings with aluminum alloy structure are widely used in the environment with high humidity, acid rain, bad climate change or coastal areas.

(6) Non stick water, good water tightness, waterproof, put an end to water leakage. Because the aluminum alloy structure of the aluminum alloy building system is integrated extrusion forming with aluminum alloy roof materials, its connection form can be perfectly combined with roof materials to achieve zero leakage and waterproof, and the aluminum processing materials are not sticky to water, and are not afraid of water leakage and corrosion.

(7) Recyclable materials are really green materials. The recovery cost of aluminum alloy material is very low, and the energy consumption is only 5% of electrolytic aluminum. The recycling rate is high, the recovery rate can reach more than 90% (more than 5 times of the steel recovery rate), and the price difference between aluminum ingot and aluminum ingot is basically small, so it is a typical green environmental protection material.

(8) Green processing can be realized. The use of aluminum alloy structure can realize fully assembled construction, reaching the standard of modular building and building industrialization. The construction site has no noise, no dust and no pollution to water and gas, which is a typical green material and green construction.

(9) Save land, energy and construction costs. In the case of the same span, the structural section is greatly reduced (about 1 / 8 of the steel structure section), which can increase the use area of the building by about 6%, reduce the space waste by about 10%, and save land and energy. At the same time, the construction cost is greatly saved.

Therefore, replacing steel structure with aluminum alloy structure can make building engineering and construction green and environmental protection, and can greatly save resources, energy and construction and maintenance costs, and has significant economic and social benefits. Accelerate the process of chemical industry in China's cities, ensure the rapid and sustainable development of national economy and improve the quality of economic growth and social civilization development. At the same time, it can expand the use field and market share of aluminum, and promote the development of aluminum processing (especially extrusion processing) and technological progress.


8. Application of aluminum alloy structural extrusion materials for green buildings and typical engineering examples

As a kind of building material, aluminum alloy has a series of advantages which can not be replaced by other building materials. The aluminum alloy structure is stable, and can adopt the patent design of unique geodesic structure, with high stability, compact structure, large net span, and the maximum span can reach 300 meters. The structural strength can adapt to various adverse environmental conditions such as unbalanced wind load and snow load.

Aluminum alloy structure has high cost performance, corrosion resistance, no need for regular maintenance and anti-corrosion treatment, permanent sealing technology and unique design ensure no water leakage, good sound insulation and sound absorption effect, single node can bear at least 50kg hanging weight, and the maximum internal self-bearing capacity is more than 200t. It can directly lift light and sound without additional devices.

In addition, it is widely used in the construction of multi-functional stadiums, skating rinks, various supporting commercial facilities and other large-scale civil public building projects. Aluminum alloy structure in the construction of swimming pools and skating rinks can play the incomparable advantages of other materials. Different from other gymnasiums, water vapor evaporation is very serious in the natatorium, especially after the disinfection components in the pool water evaporate, it will seriously corrode other metal materials in the natatorium. If the swimming pool adopts steel structure, the stability of the whole stadium will be affected. On the contrary, the aluminum alloy structure is corrosion-resistant, can well resist the erosion of water vapor, protect the structure of the venue from loss, and beautiful and durable.

Aluminum alloy space structure has strong modern sense and convenient construction, so it has broad application prospects in sports, performing arts, environmental protection and other large-span landmark buildings. Aluminum alloy is a new type of metal material mainly promoted by "lightweight alloy materials and structural components". Lightweight aluminum alloy materials can replace traditional steel, wood and other building materials. It meets the requirements of "energy-saving and environmental protection building materials" and is the development direction of green buildings in the future.


9. Summary

1. Compared with other building materials, aluminum alloy extrusion material has a series of incomparable excellent characteristics. It is an ideal green building structural material, which meets the requirements of "energy saving and environmental protection building materials", and is the development direction of green building in the future.

2. Green building aluminum alloy structural extrusion materials have many varieties, complex shapes, wide range of specifications, high technical requirements, and difficult production. Therefore, it is required to optimize the alloy composition, design and manufacture high-quality molds with various special structures, and optimize casting, extrusion, heat treatment and finishing to produce high-quality extruded structural materials in large quantities. It can promote the development of extrusion technology.

3. The industrialization, mass production and wide application of green building aluminum alloy structural extrusion materials can promote the development of green building industry in China, accelerate the development of industrialization and urbanization in China and improve its level, ensure the rapid and sustainable development of China's national economy, expand the application field of aluminum materials and promote the development of aluminum processing industry.

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