1. What is aluminum alloy?
Aluminum alloy is the most widely used type of nonferrous metal structural material in industry, and has been widely used in aviation, aerospace, automobile, machinery manufacturing, shipbuilding and chemical industries.
Pure aluminum is divided into two categories: smelting products and pressure-processed products. The former is represented by the chemical composition Al, and the latter is represented by the Chinese pinyin LV (aluminum, industrial use). Aluminum alloys can be divided into two categories according to the processing method: deformation aluminum alloys and casting aluminum alloys.
Characteristics, advantages and disadvantages of aluminum alloy
Compared with commonly used steel materials, aluminum has the following important characteristics and advantages. Based on these characteristics and advantages, aluminum and its alloys are widely used in many fields.
Advantages of Aluminum
1. Aluminum is 3 times lighter than iron.
2. Aluminum has good electrical and thermal conductivity, and is resistant to oxidation. Its thermal conductivity is 16.79 times higher than that of stainless steel, saving fuel and time.
3. Aluminum is a metal with excellent thermal conductivity. It does not rust and is resistant to many forms of corrosion, so products made of aluminum tend to have a much longer service life than products made of other metals, and it also helps reduce the negative impact on the environment.
4. Due to the properties of aluminum products, they are easy to recycle and do not lose their natural properties during the recycling process, which is conducive to environmental protection cycles.
Disadvantages of Aluminum
1.Aluminum has a relatively low hardness and poor wear resistance.
2.The volume shrinkage of aluminum during solidification is relatively large, about 6.6%
3.The linear expansion coefficient of aluminum is relatively high
4.The melting point of aluminum is relatively low, and the use temperature of aluminum and aluminum alloys cannot exceed 200 °C, so its high-temperature use is limited. The elastic modulus of aluminum is only 1/3 of that of steel.
5.The electrode potential of aluminum is very negative, so when aluminum comes into contact with dissimilar metals, it is easy to act as an anode and produce severe galvanic corrosion.
2.Aluminum Alloy Development History
It was not until 1825 that humans first produced a few milligrams of aluminum powder. Aluminum was discovered late, and aluminum smelting technology matured even later. Whether as a metal element discovered by humans or as a structural material, aluminum and its alloys are inferior to other metals. However, the emergence of aluminum and aluminum alloys has greatly promoted the development of industrial civilization, especially aerospace technology and industry.
3.The road to change for aluminum alloys
Aluminum alloy is the most widely used type of non-ferrous metal structural material in industry. It has been widely used in aviation, aerospace, automobiles, consumer electronics, machinery manufacturing, shipbuilding and chemical industries. The following will introduce the transformation of aluminum alloy from the fields of aviation, aerospace, automobiles, consumer electronics, etc.
Aerospace “Aluminum” Analysis of the Development Stages of Aviation Aluminum Alloys
Aviation aluminum is a kind of ultra-high strength deformable aluminum alloy, which is currently widely used in the aviation industry. It has good mechanical and processing properties, good plasticity after solution treatment, good heat treatment strengthening effect, generally has high strength and good toughness below 150°C (or even higher), and is an ideal structural material. In addition, aviation aluminum is light in weight and has a significant lightweight effect. It has replaced steel and occupies a dominant position in current aviation materials. Aviation equipment has high requirements for aluminum and is an important high-end application market for aluminum.
Advantages of Aluminum for Aviation
Application advantages: Aluminum alloy will also be the main structural material for domestic large aircraft development due to its high specific strength, good forming and processing performance.
Application parts: wing skin, wing long stringer, upper and lower edge strips of wing beam, web, fuselage long stringer, seat slide rail, keel beam, side frame, fuselage skin, lower fuselage wall panel, main floor stringer, etc.
Application proportion: A380-800 Airbus aluminum alloy material accounts for the largest proportion, reaching 61%, A350-900XWB Airbus aluminum alloy material accounts for 20%, Boeing 787-8 Airbus aluminum alloy material accounts for 15%-20%.
Commonly used aluminum alloy series
The aluminum alloys used in large aircraft structures in various countries around the world today are mainly high-strength 2××× series (2024, 2224, 2324, 2424, 2524, etc.) and ultra-high-strength 7××× series (7075, 7475, 7050, 7150, 7055, 7085).
Development direction of aluminum for aviation
The future research focus of aluminum alloys will be mainly on the following aspects: aluminum-lithium alloys, aluminum-based composite materials and superplastic forming aluminum alloys.
Aluminum-lithium alloy
Aluminum-lithium alloy is a multi-component aluminum alloy containing lithium. Lithium is the lightest metal element. For every 1% increase in lithium in aluminum alloy, the density can be reduced by 3% and the modulus can be increased by 5%. In addition to the advantages of light weight, high modulus and high strength, aluminum-lithium alloy also has excellent fatigue resistance and good low-temperature toughness. Its strength is comparable to that of 2024, 7075 and other aluminum alloys. In view of this, aluminum-lithium alloy has been deeply loved by the aerospace industry. As a new type of aerospace structural material, it has become a hot spot for developed countries such as the United States, Britain, France and Russia to compete for research and development.
Aluminum-based composite materials
Aluminum-based composite materials have attracted widespread attention due to their many advantages, such as low density, high specific strength and specific stiffness, large specific elastic modulus, good electrical and thermal conductivity, high temperature resistance, oxidation resistance, corrosion resistance, and flexible preparation process.
For a long time, aluminum-based composite materials have been used in a variety of ways, such as complex preparation process, strict requirements on environment and equipment, and high cost.
Superplastic forming of aluminum alloys
Superplastic forming of aluminum alloy is achieved by deformation heat treatment to obtain ultrafine grains less than 10μm. These ultrafine grain alloys can obtain superplasticity above the semi-melting point and at low strain rate conditions, and can be formed into light-weight, low-cost, and complex-shaped components that are difficult to obtain by traditional methods. They also have many advantages such as low forming pressure, high mold life, and one-time precision forming.
Analysis of “Aluminum” in Consumer Electronics Development Stages of Aluminum Alloys in Consumer Electronics
Aluminum alloy is the most common nonferrous metal product. Among them, the ones that are most closely related to us are aluminum products for consumer electronic appliances. Aluminum alloy is mainly reflected in consumer electronic products in the form of casings, frames, radiators and aluminum tubes.
Market Analysis of Aluminum for Consumer Electronics
At present, the scale of the consumer electronics market has entered a stable development stage. In mature markets, second-time purchases have become the mainstream. Consumers and consumer electronics companies are paying more and more attention to the appearance design and material technology of products.
The White Paper on Aluminum Use in China’s Consumer Electronics Industry (2016) shows that the sample companies used nearly 20,000 tons of aluminum in the finished products sold in the domestic consumer goods market in 2016, a year-on-year increase of nearly 35%, much higher than the growth rate of the consumer electronics market in the same period.
It is estimated that in 2016, the domestic demand for aluminum in the four consumer electronics fields of mobile phones, tablets, mobile power supplies, and televisions will be about 120,000 tons, and it is expected to increase to nearly 20 tons in 2018.
Aluminum Rising Star for Consumer Electronics – 7075 Alloy
The “bending gate” of iPhone 6 plus broke the hearts of a generation of Apple fans. In order to solve the problem of low bending resistance of iPhone 6 plus, the aluminum industry suggested that Apple use the ultra-high-strength aluminum alloy 7075 plates used in the aerospace industry to process the body. Both iPhone 6S and iPhone 6S plus were manufactured using 7075 alloy plates produced by Alcoa, achieving the expected good results. The bending resistance was greatly improved, and the problem of bending due to a fall disappeared, and deformation did not occur.
7075 Alloy Introduction
The 7075 alloy was developed by the American Aluminum Company for World War II aircraft and was used to manufacture large bombers and fighters. It was finalized in 1944 and the grade before July 1954 was 75S. In July 1954, it was registered with the American Aluminum Association and changed to a unified four-digit grade 7075.
For example, the front fuselage long stringer, passenger observation window frame, middle fuselage long stringer, keel beam edge strip, keel beam web, floor turning beam, middle and rear fuselage long stringer and cargo door frame, nose long stringer and edge strip, cabin door frame, etc. of the C919 aircraft are all made of different 7075 alloy materials. It can be said that without the support of 7075 aluminum alloy, such a high-value, lighter, more comfortable and faster large passenger aircraft cannot be built.
Application of 7075 alloy in mobile phone industry
The new iPhone is not the only smart phone that uses this super-strong material in the world’s mobile phone body. The ultra-thin bodies of Samsung’s Note5 and S6 edge+ benefit from the use of 7075 alloy. Due to the excellent performance of 7075 alloy, the stability of the bodies of the two smart phones has reached an unprecedented new height. Since then, there has been no bending or damage.
Mobile phones and electronic products: The shortcomings of aluminum shells need to be fully addressed
There are many kinds of electronic products, and the aluminum materials used are also varied, with styles that vary greatly. Although the amount of a single product is not much, the output of electronic products is large, in the millions, tens of millions, and even hundreds of millions, and the replacement is very fast. Aluminum is widely used in the manufacture of mobile phone bodies and electronic product shells. Now it is almost impossible to find electronic products that do not use aluminum.
At present and in the future, the trend of thinner and lighter mobile phones is an unstoppable trend, which requires stronger and better body materials to support it. In the future, more domestic mobile phones will definitely use 7xxx series alloy thick plates as body materials, but the plates used now are all produced by Alcoa, and the import price is as high as 70,000 yuan/t, which is about 3.9 times the price of 3xxx series alloys. In addition to the fact that the production process of 7075 alloy is much more complicated than that of other alloys, foreign companies have also seen that China cannot currently produce aluminum alloy thick plates of this type of mobile phone grade, and rare goods are in great demand.
Therefore, China must get rid of this dilemma as soon as possible and make up for this shortcoming. China’s aluminum processing equipment is fully capable of producing this kind of aluminum plate. In fact, as early as 1957, Harbin Aluminum Processing (code-0-Factory, now Northeast Light Alloy Co., Ltd.) successfully trial-produced aviation-grade B95 (Soviet brand, equivalent to 7075) alloy materials with the help of Soviet experts.
Of course, the processing technology of 7xxx alloy mobile phone body alloy plates, including CNC cutting and anodizing coloring, is much more difficult than 6xxx series alloy plates. Whether these problems can be solved smoothly will be the key to whether the alloy plates can be promoted and applied in domestic mobile phones.
“Aluminum” in the automotive industry: Analysis of the development stages of aluminum alloys for automobiles
The development of energy-saving and environmentally friendly cars is an urgent need to ease the contradiction of fuel supply and reduce exhaust emissions. It is also an inevitable choice for the sustainable and healthy development of my country’s automobile industry in the future. As a common key technology for energy-saving cars and new energy vehicles, automobile lightweighting has also been widely promoted and applied.
The development of the world’s automobile industry faces three major themes: energy saving, environmental protection and safety. According to the test verification of relevant research institutions, a 10% weight reduction of gasoline passenger cars can reduce fuel consumption by 3.3%, and a 15% weight reduction can reduce fuel consumption by 5% accordingly.
Lightweighting of the body is an inevitable choice for new energy vehicles to increase the “range” by increasing the number of battery packs. With the rapid development and popularization of new energy vehicles, lightweighting of the body has also received more and more attention. Advanced high-strength steel, aluminum-magnesium light metal, carbon fiber and other composite materials have become the three main directions of lightweight development.
Application of aluminum alloy in automobiles
Aluminum alloys are widely used in automobiles. Power and transmission systems, body and interior and exterior systems, heat exchange systems, wheels, etc. all have parts made of aluminum alloy materials.
With the development of lightweight automobiles, the rapid growth of aluminum alloy applications in the future will mainly focus on body structural parts such as panels and body-in-white. The proportion of all-aluminum bodies will increase from the current 4% to 18%, with an average annual compound growth rate of more than 16%.
By 2025, the proportion of models with all-aluminum bodies will reach 30%, the total amount of aluminum used in global car bodies will reach 8.7 million tons, and the aluminum industry for car bodies will experience explosive growth.
New directions in the research, development and application of automotive aluminum
With the increasing degree of automobile aluminumization, it is required to develop new aluminum alloys for different purposes and new aluminum materials of different specifications and varieties. This will greatly promote the development of aluminum alloys and their processing technology, and promote the application of aluminum materials in the automobile industry. It can be foreseen that aluminum materials will partially replace steel and become the basic material of the automobile industry. The expansion of automobile aluminumization in the future will inevitably rely on the balance between the demand for aluminum materials and the production cost. Reducing the cost of aluminum materials and improving production efficiency are the future directions of efforts:
1. Research and development of new aluminum alloy body materials
2. Research and development of anti-collision guards and rigid door structural parts
3. Research and development trends of rotating parts
4. Research and development of new aluminum alloy heat exchange materials
5. Research and development of weldable medium-strength aluminum alloy plates for commercial vehicle fuel tanks and air compressor cylinders
6. Research and development of forged aluminum alloy wheels and structural parts
