Nature, purpose and classification of aluminum
The use of a substance depends largely on the nature of the substance. Because aluminum has many excellent properties, aluminum has extremely wide uses.
(1)The density of aluminum is very small, only 2.7g/cm. Although it is relatively soft, it can be made into various aluminum alloys, such as duraluminum, ultra-duraluminum, rust-proof aluminum, cast aluminum, etc. These aluminum alloys are widely used in aircraft, automobiles, trains, ships and other manufacturing industries. In addition, space rockets, space shuttles, and artificial satellites also use large amounts of aluminum and its alloys. For example, a supersonic aircraft consists of approximately 70% aluminum and its alloys. Aluminum is also used in large quantities in ship construction, and the amount of aluminum used for a large passenger ship often reaches several thousand tons.
(2)The conductivity of aluminum is second only to silver and copper. Although its conductivity is only 2/3 of that of copper, its density is only 1/3 of that of copper. Therefore, when transporting the same amount of electricity, the quality of aluminum wire is only half that of copper wire. The oxide film on the surface of aluminum not only has corrosion resistance, but also has certain insulation properties, so aluminum is widely used in the electrical appliance manufacturing industry, wire and cable industry, and radio industry.
(3)Aluminum is a good conductor of heat. Its thermal conductivity is three times greater than that of iron. Aluminum can be used in industry to make various heat exchangers, heat dissipation materials and cookware.
(4)Aluminum has good ductility (its ductility is second only to gold and silver), and can be made into aluminum foil thinner than 0.01mm at 100℃~150℃. These aluminum foils are widely used for packaging cigarettes, candies, etc. They can also be made into aluminum wires, aluminum strips, and can be rolled into various aluminum products.
(5)The surface of aluminum is not easily corroded due to its dense oxide protective film. 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 a silver-white luster (generally, the color of metals is mostly black when they are in powder form) and is often used as coatings, commonly known as silver powder and silver paint to protect iron products from corrosion and are beautiful.
(7)When aluminum burns in oxygen, it can release a large amount of heat and dazzling light. It is often used to make explosive mixtures, such as ammonium aluminum explosives (made from a
mixture of ammonium nitrate, charcoal powder, aluminum powder, smoke black and other combustible organic substances), combustion mixtures (such as bombs and shells made of thermite, which can be used to attack hard-to-fire targets or tanks, cannons, etc.) and lighting mixtures (such as containing 68% barium nitrate, 28% aluminum powder, and 4% shellac).(8)Thermit is often used to melt refractory metals and weld steel rails. Aluminum is also used as a deoxidizer in the steel-making process. Aluminum powder is evenly mixed with graphite, titanium dioxide (or other high-melting-point metal oxides) in a certain ratio, coated on the metal, and calcined at high temperatures to make high-temperature resistant cermet. It has important applications in rocket and missile technology.
(9)Aluminum plates also have good reflective properties to light, and reflect ultraviolet light more strongly than silver. The purer aluminum, the better its reflective ability. Therefore, they are often used to make high-quality mirrors, such as solar stove mirrors.
(10)Aluminum has sound-absorbing properties and good sound effects, so aluminum is also used in radio rooms, indoor ceilings in modern large buildings, etc.
Classification of aluminum
(1)Pure aluminum: Pure aluminum is divided into three categories according to its purity: high-purity aluminum, industrial high-purity aluminum and industrial pure aluminum. Welding is mainly made of industrial pure aluminum. The purity of industrial pure aluminum is 99.7%^}98.8%. Its grades are L1, L2, L3, L4, L5, and L6.
<2) Aluminum alloy: Add alloying elements to pure aluminum to obtain an aluminum alloy. According to the processing characteristics of aluminum alloys, they can be divided into two categories: deformed aluminum alloys and cast aluminum alloys. Deformed aluminum alloys have good plasticity and are suitable for pressure processing.
Deformed aluminum alloys can be divided into rust-proof aluminum according to their performance characteristics and uses
The main aluminum alloy grades are: 1024, 2011, 6060, 6063, 6061, 6082, 7075
Aluminum brand:
The 1××× series is: pure aluminum (aluminum content is not less than 99.00%)
The 2××× series is: aluminum alloy with copper as the main alloying element
The 3××× series is: aluminum alloy with manganese as the main alloying element
The 4××× series is: aluminum alloy with silicon as the main alloying element
The 5××× series is: aluminum alloy with magnesium as the main alloying element
The 6××× series is: aluminum alloy with magnesium as the main alloying element and Mg2Si phase as the strengthening phase
The 7××× series is: aluminum alloy with zinc as the main alloying element
The 8××× series is: aluminum alloys with other elements as the main alloying elements
The 9××× series is: spare alloy group
The second letter of the brand indicates the modification of the original pure aluminum or aluminum alloy, and the last two digits indicate that the last two digits of the brand identify different aluminum alloys in the same group or indicate the purity of aluminum.
The last two digits of the 1××× series of grades are expressed as the percentage point of the lowest aluminum content. The second letter of the brand indicates the modification of the original pure aluminum.
The last two digits of the 2×××~8×× series of grades have no special significance and are only used to distinguish between different aluminum alloys in the same group. The second letter of the brand indicates the modification of the original pure aluminum.
* Status of aluminum and aluminum alloys:
Code F×× is: free machining state
O×× is: annealed state
H×× is: work-hardened state
W×× is: solid solution heat treatment state
T× is: heat treatment state (different from F, O, and H states)
*H×× subdivision status:
The first digit after H indicates: The basic handler for obtaining this state is shown below.
H1: Simple work-hardened state
H2: Work hardened and partially annealed state
H3: Work hardening and stabilization state
H4: Condition of work hardening and painting treatment
The second digit after H: indicates the work hardening degree of the product. For example: 0 to 9 means that the work hardening degree is getting harder and harder.
* Rolling of aluminum alloy plate and strip:
According to the rolling temperature, it can be divided into hot rolling, warm rolling (medium temperature rolling) and cold rolling
According to the arrangement of rolling mills, it can be divided into single stand rolling, semi-continuous rolling and continuous rolling.
Karen
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