Research progress of aluminum and aluminum alloys and related application prospects

First, the melting process

The casting process is:

(1) Application computer: The mathematical model is used to calculate the optimal fuel control system. It is reported that the variable oxygen/air/fuel nozzle can be used to increase the melting speed, reduce fuel consumption and improve the life of the refractory.

(2) Studying the problem of inclusion in static furnace: the uneven temperature in the molten pool causes convection of aluminum water, large inclusions are not affected by convection of aluminum water, small inclusions are caused by slow precipitation, and the mechanism is different, so the data provided can be used Improve the static furnace geometry.

(C) Casting 2000 series, 6000 series, 7000 series macroscopic segregation problem in the alloy.

(4) The computer-aided production system is used in the electronically controlled foundry, and is equipped with many process controllers and control networks.

(V) To carry out research on aluminum water degassing agent, currently ideal is SF6.

(6) To carry out research on the on-line degassing system of porous refractories. At present, smelting process systems mostly use SNIF and ALPUR.

(VII) Research on the production of thin plates and aluminum alloy plates by continuous casting and rolling mills. The British company David and Oxford University jointly developed the second generation twin-roll continuous casting machine, which has the characteristics of high speed and ability to produce thinner plates.

Second, grain refinement should be vigorously promoted in the aluminum industry

In the melting of aluminum and aluminum alloys, the internal stress generated by the change of the metallurgical structure tends to cause cracks in the metal ingot, which greatly reduces the aluminum processing yield and increases the cost of the aluminum processed material. In order to solve this problem, it is necessary to make When the metal finally solidifies, the grain structure of the metal is refined, and the columnar crystal structure is eliminated to reduce the crack of the ingot to improve the plasticity of the ingot. Therefore, the development and promotion of the aluminum alloy grain refiner has become the development of the aluminum industry and the need for technological advancement. There are many types of aluminum alloy grain refiners, such as aluminum titanium boron refiner, titanium boron refiner, aluminum titanium carbon refiner and aluminum titanium intermediate alloy. There is no complete theory on the mechanism of action of aluminum alloy grain refiners, and countries are carrying out research work in this area.

The application of aluminum alloy grain refiner in China is relatively late. In recent years, due to the technological requirements of imported production lines abroad, it has been applied in some aluminum production, and its role has also begun to be recognized. In 1986, the Northeast Institute of Technology Developed into a rod-shaped Al-Ti-B refiner in China, and was mass-produced and supplied to domestic aluminum processing enterprises in 1987. Later, in the county, Shenyang, Zhengzhou and other places, the development and production of grain refiner was also started. And also achieved some results in the application.

Third, the use of laser processing aluminum technology

When the aluminum and aluminum alloy materials are irradiated with CO ₂ laser, 95% of the light is reflected. However, once the aluminum surface is melted, a molten pool is formed, and the ability to absorb light energy is sharply increased. This phenomenon can be used to solve the high reflectivity of the aluminum surface. The problem is that the laser aluminum cutting machine is designed based on this principle.

At present, a laser aluminum cutting machine with a power of 1 kW can only cut 3 mm thick 5052 aluminum alloy, while cutting steel can cut a 9 mm thick plate.

In addition to the convex lens concentrating, this aluminum laser cutting machine realizes chipless cutting for blowing away the residue, and also uses a double gas nozzle. The thin plate can be welded by laser pulse to a thickness of 2 to 100 μm.

The aluminum surface is etched by a laser and the surface quality of the aluminum is improved by laser surface fusion welding. Laser-processed aluminum is under development. In order to overcome the shortcomings of aluminum heat conduction, high-power laser aluminum processing machines and 3D laser-cut aluminum equipment are being developed.

Fourth, aluminum alloy surface modification technology

Aluminum alloy has high specific strength, good workability and corrosion resistance, and is widely used in many products. In recent years, the performance requirements of these products have been improved, so aluminum alloys are required to have wear resistance, heat resistance and corrosion resistance. Higher functions, especially for the improvement of automotive lightweighting requirements, require aluminum surface modification technology.

See Table 1 for various aluminum alloy surface modification techniques.

Table 1 Surface modification method of aluminum alloy and its characteristics

Five, aluminum lithium alloy research

Since the density of lithium is small, each 1% lithium added to aluminum can reduce its density by 3%, and the stiffness can be increased by 1%, the corresponding structural quality can be reduced by 10% to 65%, and the quality of the welded structure can be reduced by 20%. ~ 25%, the cost of aluminum-lithium alloy materials is only 1/10 of the cost of polymer composites. Taking the former Soviet Union as an example, the aluminum-lithium alloy semi-finished products produced by it are shown in Table 2.

Table 2 Semi-finished products of aluminum-lithium alloy 1420, 1450, 1440 produced in batches in the former Soviet Union

Sixth, a new type of aluminum alloy wheel

The process of aluminum alloy for automobile wheels is mature, and its weight is only about 50% of that of steel wheels. KS6161 alloy is considered to be an ideal aluminum alloy for automobile wheels. The mechanical properties of KS6161 alloy and other alloys are shown in Table 3.

Table 3 Comparison of mechanical properties of KS6161 alloy and other alloys

Seven, the development of aluminum matrix composites

There are two development directions worthy of attention in aluminum matrix composites: aluminum matrix composites and laminate materials. The aluminum matrix composite consists of an aluminum based alloy and high strength fibers embedded therein. Fibers include long fibers, short fibers, and whiskers or particulates. The decisive factors for expanding the range of applications for aluminum-based fiber reinforced composites are fiber prices and production costs. A laminate composite material currently developed is a composite material made of an aluminum strip and a fiber-reinforced plastic strip bonded together.

The application of aluminum matrix composites is as follows:

(I) Application in the aerospace industry: Aerospace is the earliest field of application of aluminum-based composite materials. It mainly uses aluminum-based composite materials to build cargo space trusses and satellite parabolic antennas.

(2) Application in aviation industry: Fiber-reinforced resin-based composite materials are mainly used for fighter aircraft to reduce aircraft quality.

(III) Application in the automotive industry: used in key parts of automobile engines.

Eight, ultra-vacuum materials

All the positive and negative electron impact rings in the Japanese detachable ring intersection storage accelerator are made of aluminum alloy. The aluminum alloy is used because the aluminum alloy attenuates the induced radiation and is much stronger than the stainless steel, and emits very little gas. . It has been proved that this aluminum alloy profile is an excellent material for ultra-high vacuum of aluminum, and the gas discharge rate is 1×10 ^{- 14} Torr/(s·cm ² ).

Nine, aluminum for fusion reaction

New materials for nuclear fusion devices are being developed all over the world, and high-purity aluminum with elements Li, Mg, Si, and V is added to obtain materials with low residual induced radioactivity. The materials under study include Al-Mg-Si, Al-Mg, Al-Si, Al-V, Al-V-Si, Al-Mg-V, Al-Mg-Li, and SAP, etc., but many problems such as heat resistance, corrosion resistance, radiation hazard, etc. remain unresolved It is expected that there will be further improvements in the future.

X. Development of the aluminum industry

Aluminum is a very young metal. During the 44 years from 1944 to 1988, the annual output of aluminum in the world has increased by 19 times. The development of aluminum is so fast, indicating that aluminum itself has many advantages, so aluminum is constantly producing and growing. In the field, the generation of steel on behalf of the copper substitute wood also replaces the clay, an important form of the development of aluminum is the "replacement."

In the short-term development of aluminum, demand has played a huge role in promoting. For example, during the Second World War, due to the manufacture of aircraft, the rapid development of aluminum was promoted. From 1940 to 1943, the output of aluminum increased from 230,000 tons to 1.46 million tons, and 1960~ Aluminum increased from 4.46 million tons to 10.2 million tons in 1970, due to the extensive use of aluminum-based steel in the construction industry.

The automobile industry is an important pillar industry in developed countries. In the current fierce competition in the automotive industry, a new direction of automobile “quantification of vehicles” – “total steel” is an inevitable trend;

(1) Energy saving and energy saving. 100kg aluminum can be used to replace steel 200kg, which can save 8% of oil; 300kg can save oil by 24%.

(2) Environmental protection. Due to the difficulty in recycling plastics and steel, the garbage caused by automobiles has become a disaster. Aluminum recycling is good, metal recycling is extremely important, and aluminum can be recycled more than 85%.

In the coming period, automotive aluminum will become a new development direction, and technological advancement should be accelerated to meet the lighter needs of the automotive industry with new aluminum materials.

Before 1995, all the cans required by China were the single-type aluminum materials with the largest import volume in China. Whether the mass production of canned materials in the market is a national aluminum processing industry is modernized and reached the advanced level. Sign. Under the cooperation of the relevant departments of the state, the southwest aluminum processing plant has formed the annual production capacity of 10,000 tons of high-performance ultra-thin aluminum and aluminum alloy strips with 1850mm cold rolling mill, which has enabled China's canning industry to embark on raw material products. The road to self-production integration.

Since 1994, China has witnessed a new upsurge in the construction of cans production lines. At the same time, the original production line technology has been transformed, and the production speed has generally increased substantially, mostly at 1,600/min, with a total design capacity of 600 million/a.

China's aluminum foil industry has entered the forefront of the world, basically achieving the modern production of aluminum foil, the quality is equivalent to the international level, while China has begun to master the production technology of large-scale high-speed aluminum foil rolling mill, some high-tech electronic aluminum foil factory and medium-sized aluminum foil factory are under construction, large The aluminum foil factory cooperated with foreign companies and Hong Kong businessmen to expand and expand the joint venture, creating a new milestone in the Chinese aluminum foil industry.

In 1989, China's first aluminum alloy wheel enterprise - Dhaka Hub Co., Ltd. was completed and put into production in Qinhuangdao, with a designed production capacity of 400,000 / a. By the end of 1995, there were 10 aluminum alloy wheel hub enterprises, with a total production capacity of 6 million/a.

China's modern aluminum strip equipment has reached a considerable level, especially four large high-speed rolling mills (including 2 CVC mills) with world-class installed capacity, modern rolling mill production capacity has an absolute advantage, the entire strip and strip industry has begun to enter the market The economic track is moving in the direction of scale, efficiency, level, and structural optimization.