Aluminum Alloy
Aluminum (Aluminium) is a metal element, the element symbol is Al, and the atomic number is 13. Its element is a silver-white light metal. Extensible. Commodities are often made into rods, sheets, foils, powders, ribbons and filaments. In moist air, it can form an oxide film that prevents metal corrosion. Metal aluminum and aluminum alloy are widely used, mainly used in aviation, construction, automobile and other industries
The content of aluminum in the earth’s crust is second only to oxygen and silicon, ranking third. It is the most abundant metal element in the earth’s crust, and its reserves rank second among metals. Among the metal varieties, it is the second largest metal category after steel. Aluminum materials can be divided into pure aluminum and aluminum alloys.
Pure aluminum can be divided into three purity grades according to purity:
- High-grade pure aluminum: 99.93~99.999
- Industrial high-purity aluminum: 99.85~99.9
- Industrial pure aluminum: 98~99.7
Aluminum alloy is an alloy based on aluminum with a certain amount of other alloying elements added, and it is one of the light metal materials. In addition to the general characteristics of aluminum, aluminum alloys also have some specific characteristics of alloys due to the different types and quantities of alloying elements added. The density of aluminum alloy is 2.63～2.85g/cm3, with high strength (σb is 110～650MPa), the specific strength is close to that of high alloy steel, the specific stiffness exceeds that of steel, and it has good casting properties and plastic workability, and good electrical conductivity. , thermal conductivity, good corrosion resistance and weldability, can be used as a structural material, and has a wide range of applications in aerospace, aviation, transportation, construction, electromechanical, light and daily necessities.
Aluminum’s light weight and corrosion resistance are two outstanding features of its performance. In addition, aluminum material also has the following characteristics:
1. The density of aluminum is very small, only 2.7 g/cm³. Although it is relatively soft, it can be made into various aluminum alloys, such as hard aluminum, super hard aluminum, rust-proof aluminum, cast aluminum, etc. These aluminum alloys are widely used in aircraft, automobile, train, ship and other manufacturing industries. In addition, space rockets, space shuttles, and artificial satellites also use a large amount of aluminum and its aluminum alloys. For example, a supersonic aircraft consists of about 70% aluminum and its alloys. Aluminum is also used in large quantities in ship construction, and a large passenger ship often uses several thousand tons of aluminum.
2. The conductivity of aluminum is second only to silver, copper and gold. Although its conductivity is only 2/3 of that of copper, its density is only 1/3 of that of copper. Therefore, the quality of aluminum wire is only copper wire for the same amount of electricity. half of . The oxide film on the surface of aluminum not only has the ability to resist corrosion, but also has a certain degree of insulation, so aluminum has a wide range of uses in the electrical manufacturing industry, the wire and cable industry and the radio industry.
3. Aluminum is a good conductor of heat. Its thermal conductivity is 3 times greater than that of iron. Aluminum can be used in industry to manufacture various heat exchangers, heat dissipation materials and cooking utensils.
4. Aluminum has good ductility (its ductility is second only to gold and silver), and it can be made into aluminum foil thinner than 0.01 mm at 100 ℃ ~ 150 ℃. These aluminum foils are widely used for packaging cigarettes, candies, etc., and can also be made into aluminum wires, aluminum strips, and can be rolled into various aluminum products.
5. Due to the dense oxide protective film on the surface of aluminum, it is not easy to be corroded. It is often used to manufacture chemical reactors, medical equipment, refrigeration equipment, petroleum refining equipment, oil and natural gas pipelines, etc.
6. Aluminum powder has silver-white luster (generally, the color of metal in powder form is mostly black). It is often used as paint, commonly known as silver powder and silver paint, to protect iron products from corrosion and to be beautiful.
7. Aluminum can emit a lot of heat and dazzling light when burned in oxygen. It is often used in the manufacture of explosive mixtures, such as ammonium-aluminum explosives (mixed with ammonium nitrate, charcoal powder, aluminum powder, smoke black and other combustible organic substances), Combustion mixtures (such as bombs and shells made of thermite can be used to attack difficult-to-fire targets or tanks, artillery, etc.) and lighting mixtures (such as barium nitrate 68%, aluminum powder 28%, shellac 4%).
8. Thermite is often used to smelt refractory metals and weld rails. Aluminum is also used as a deoxidizer in the steelmaking process. Aluminum powder, graphite, titanium dioxide (or oxides of other high melting point metals) are uniformly mixed in a certain ratio, then coated on metal, and calcined at high temperature to make high temperature resistant cermet, which has important applications in rocket and missile technology .
7. The reflection performance of aluminum plate to light is also very good. It reflects ultraviolet rays stronger than silver. The purer the aluminum, the better the reflection ability. Therefore, it is often used to manufacture high-quality reflectors, such as solar cooker reflectors.
8. Aluminum has sound-absorbing properties and good acoustics, so aluminum is also used for ceilings in broadcast rooms and modern large-scale buildings. Low temperature resistance, when aluminum is low in temperature, its strength increases without brittleness, so it is ideal for low temperature device materials, such as refrigerators, freezers, and production devices for Antarctic snow vehicles.
9. Aluminum-air battery, as the name suggests, is a new type of battery using aluminum and air as battery materials. It is a pollution-free, long-lasting, stable and reliable power supply, and is a very environmentally friendly battery. The structure of the battery and the raw materials used can be changed according to different practical environments and requirements. It has great adaptability and can be used both on land and in the deep sea. Signal battery.
Classification of aluminum alloys:
Aluminum alloys are divided into deformed aluminum alloys and cast aluminum alloys according to their composition and processing methods. Deformed aluminum alloys are made by first melting and casting alloy ingredients into billets, and then plastic deformation processing, and various plastic processing products are made by rolling, extrusion, stretching, forging and other methods. Cast aluminum alloy is a blank that is directly cast into various parts by sand mold, iron mold, investment mold and die casting method after smelting the ingredients.
Deformation of aluminum alloy
Deformed aluminum alloys are semi-finished aluminum alloys such as tubes, rods, wires, and shapes made by various pressure processing methods. According to its use, it can be divided into five categories: anti-corrosion aluminum alloy, super hard aluminum, special aluminum, hard aluminum, and forged aluminum.
The main alloying elements in the commonly used anti-rust aluminum alloys are manganese and magnesium. Adding manganese can improve its corrosion resistance, adding magnesium to strengthen it and reduce its specific gravity. It is characterized by corrosion resistance, good polishability, and can maintain a bright surface for a long time. The strength is higher than that of pure aluminum, and it is mostly used in the manufacture of parts, pipes, daily necessities, decorations, etc. that are in contact with liquids. Duralumin, also known as duralumin, is an alloy of aluminum, copper, and magnesium, and contains a small amount of manganese. Copper and magnesium are more soluble in aluminum and have a strengthening effect, and manganese makes them resistant to corrosion. Hard aluminum can be used to manufacture rivets, aircraft propellers and high-strength parts on aircraft according to the content of its alloying elements; super hard aluminum is hard aluminum containing zinc, and its hardness and strength are higher than that of hard aluminum. Different varieties of super hard aluminum It is used to manufacture various structural parts and high-load parts, and is one of the important materials in the aviation industry; forged aluminum has high plasticity and high strength under normal conditions, and is used to manufacture various forgings or stamping parts, such as internal combustion engine pistons, etc.; Special aluminum is used in specific situations, with different components, and each has its own purpose.
Casting of aluminum alloys
Cast aluminum alloys are aluminum alloys used to directly cast various shapes of mechanical parts. According to the main elements added, it can be divided into Al-Si alloys, Al-Zn alloys, and Al-Mg alloys. Each system has its own brand, which is more complicated.
Application of aluminum alloy:
Aluminum and its aluminum alloys are currently one of the most widely used and most economical materials. Since 1956, the world’s aluminum output has surpassed the copper output and has always ranked first in the non-ferrous metals. At present, the output and consumption of aluminum (calculated by tons) is second only to steel, and it has become the second largest metal used by human beings. Moreover, aluminum resources are very rich. According to preliminary calculations, the mineral reserves of aluminum account for more than 8% of the constituent materials of the earth’s crust. .
Aluminum alloy has the characteristics of low density, good mechanical properties, good processing performance, non-toxicity, easy recycling, electrical conductivity, heat transfer and corrosion resistance, etc. It is widely used in marine industry, chemical industry, aerospace, metal packaging, transportation, etc. widely used in the field.
Aerospace
Aluminum alloy is the main material used in the manufacture of aircraft. Compared with the mild steel used in the manufacture of automobiles, aluminum alloys are expensive and low in density. The relative density is 2.8. Compared with the relative density of mild steel, which is 7.8, it is about one-third lighter. Although the strength is similar, for aircraft, the material Lightness is the most important, and it has strong corrosion resistance and convenient processing, so aluminum alloy is the most ideal material for manufacturing aircraft.
Marine industry
Aluminum and aluminum alloys are used more and more widely in the shipbuilding industry, from small motorboats to large 10,000-ton oil tankers, from offshore hovercraft to submarine submarines, from civilian to military industry, from fishing vessels to marine mining vessels, all of them have excellent comprehensive performance. The aluminum alloy produces ship shells, support structures, supporting facilities, pipes, etc.
Aluminum alloy is used in the marine industry, which can reduce the overall weight of the ship, improve the speed of the ship, and resist the corrosion of the ship by seawater. The aluminum alloys used in the marine industry are mainly aluminum-copper alloys, aluminum-magnesium alloys and aluminum-silicon alloys. Aluminum-copper alloys are widely used in ships in my country and Russia, but their poor resistance to seawater corrosion hinders their development in the shipbuilding industry. Aluminum-magnesium alloys are mainly used for hull shells, water pump conduits, pump housings and machine base brackets, etc. Aluminum-silicon alloy has moderate structural strength, good fluidity and strong filling ability, and is easy to produce parts with high density and complex structure, such as high-pressure valve parts, cylinder blocks, pumps, gearbox casings, turbine blades, etc.
Chemical Industry
Aluminum has good thermal conductivity, and aluminum and aluminum alloys are widely used in the production of heat exchange equipment in chemical equipment, storage tanks against concentrated nitric acid corrosion, adsorption filters, fractionation towers, pipelines and many linings. Casting aluminum alloy has good fluidity, strong filling ability, small shrinkage, not easy to form cracks, good corrosion resistance (the surface can form aluminum oxide and silicon dioxide protective film), light weight, good mechanical properties, and excellent mechanical properties. It is widely used in the manufacture of corrosion-resistant parts with complex structures, such as cylinders, pipe fittings, valves, pumps, pistons, etc. Aluminum has many special uses in chemical production. Aluminum does not produce sparks, and aluminum alloys can be used to produce containers containing volatile substances; aluminum is non-toxic, does not cause food deterioration, does not affect the appearance of goods, and does not corrode goods. Therefore, aluminum alloys are widely used in the production of food and chemical industries. equipment.
Metal packaging
Aluminum alloy can be used for metal packaging, which has the following excellent characteristics: good mechanical properties, light weight, high compressive strength, durable, easy to store and transport goods; good barrier properties, can block sunlight, oxygen and humid environments to damage items , which can extend the shelf life of items; good texture and aesthetics, aluminum alloy used as packaging has a unique metallic luster, good touch, beautiful, and improve product quality; non-toxic, easy to recycle, recyclable, saving resources and reducing environmental pollution. Aluminum alloys are widely used in beer, beverage and other food cans, mostly stamping and drawing structures. Aluminum foil utensils are beautiful, light in weight and good in heat transfer. They are used in the packaging of fast food. They have the functions of preserving freshness, flavor and non-toxicity, and are used by more and more food industries. The aluminum alloy metal hose can be squeezed and deformed, and the contents can be squeezed and used, which is simple and convenient, and is often used in the packaging of paste cosmetics.
Other industry
Aluminum alloy has high specific strength, light weight, good fluidity, strong filling ability, good corrosion resistance and low melting point, and is widely used in tractors, locomotive parts, electronic products, medical equipment, building decoration and other industries. Aluminum alloy has excellent ductility and is widely used in the daily necessities industry and the food industry. In the field of power transmission, the wires made of aluminum alloys have low cost, light weight, good corrosion resistance, heat transfer, easy electrical conductivity, and wear resistance, so people pay more and more attention. In the field of power transmission, aluminum alloys are the most used, and up to 90% of high-voltage conductor materials are aluminum products [10]. Aluminum-silicon alloy can be used as a good deoxidizer to reduce the sensitivity of steel to produce subcutaneous bubbles, and steel-making deoxidation can improve the quality of steel.