Introduction
Overview
my country is a rich country with magnesium mines, and its mineral resources account for 50% of the world's magnesium mines. The world's magnesium mine market has been impacted by my country's magnesium mines. . However, due to my lack of deep processing technology, I can only export ore powder. At the same time, due to the disorderly competition among domestic magnesium ore companies, the export price of magnesium ore powder has dropped from US$3,000-6000/ton in previous years to US$1,200/ton. Tons. Therefore, both the magnesium mining company and the national competent authority have put forward the requirements for accelerating the development of magnesium alloy deep processing technology.
The price of magnesium alloy is cheap, which is conducive to the development of deep processing technology. Due to the lack of deep processing technology of magnesium alloy, our country is rich in magnesium mines and provinces with concentrated magnesium resources such as Shanxi, Qinghai, Xinjiang and Gansu. Many township and village enterprises competed to participate in mining, and the output increased significantly year by year. As a result, the price of magnesium alloy was RMB 13-14/kg, while the price of aluminum was RMB 18-20/kg. This brought about the development of magnesium alloy deep processing technology. Extremely favorable conditions.
Because it has many advantages such as high specific strength, low density, corrosion resistance, recyclability, good thermal conductivity, anti-electromagnetic radiation, and thin-wall molding. Beginning in Europe, some automobile manufacturers began to use magnesium alloys to replace the original materials on steering wheels, doors, and engine blocks. In Japan and Taiwan, magnesium alloys are applied to the covering parts of 3C products, which improves the quality of the products and thereby enhances the competitiveness of the products.
Advantages
1. The density is small. Magnesium metal is the metal with the smallest density among widely used metals. Calculated by ρ=1.8g/cm3, magnesium alloy is 20% lighter than plastic. 30% lighter than aluminum.
2. High specific strength, that is, the ratio of strength to mass of magnesium alloy is high, and it has a certain bearing capacity.
3. Good heat dissipation performance, suitable for products with higher heat dissipation requirements. The thermal conductivity is 100 times that of PP material.
4. The modulus of elasticity is small, the rigidity is good, it is not easy to deform after long-term use, and the shock resistance is strong.
5. Good anti-electromagnetic interference and electromagnetic shielding performance.
6. The color is bright and beautiful, corrosion resistant, and can maintain the appearance quality for a long time.
7. It is an environmentally friendly material, and its waste can be recycled.
Disadvantages
1. The processing technology is difficult, the molten magnesium is flammable and explosive, and the yield of die castings is low.
2. There are many waste materials in the slag bag, runner and pouring system, which are more than double the volume of the product.
3. The price of domestic materials is cheap, but the quality is poor.
4. Due to potential corrosion, direct connection with other materials such as aluminum and steel must be avoided, which makes assembly difficult.
Applications
Electronic products
Usually used in the case of mid-to-high-end ultra-thin or smaller notebooks. The silver-white aluminum-magnesium alloy shell makes the product more luxurious, beautiful, easy to color, and can be turned into personalized powder blue and pink through the surface treatment process, which adds a lot of color to the notebook. This is engineering plastics and carbon fiber. Unmatched. As a result, aluminum-magnesium alloy has become the preferred casing material for portable notebook computers, and most manufacturers' notebook computer products use aluminum-magnesium alloy casing technology. Disadvantages: aluminum-magnesium alloy is not very strong and wear-resistant, costly, and more expensive, and it is more difficult to form than ABS (need to use stamping or die-casting process), so notebook computers generally only use aluminum-magnesium alloy on the top cover, rarely The organic type uses aluminum-magnesium alloy to make the entire chassis.
Cars, motorcycles and other vehicle parts
Using magnesium alloys to make auto parts can significantly reduce the overall weight of the car, and the fuel used in the car Approximately 60% of the car's weight is consumed by the car's own weight. Every 10% reduction in car weight can save fuel by 5.5%. Therefore, the application of magnesium alloys in car manufacturing abroad has gradually increased in recent years. But our country's development in this area has just started.
High-end architectural decoration materials
Because magnesium alloys have many unique properties that are superior to aluminum alloys, the use of magnesium alloys to make high-end luxury buildings appears abroad. With the trend of decorative materials, some domestic magnesium alloy manufacturers strongly demand the development of forming and processing technology for magnesium alloy profiles. The Ministry of Science and Technology also hopes to develop this technology as soon as possible and list it as a key national "Tenth Five-Year Plan" project.
Others
Others such as aluminum alloy additives, magnesium sacrificial anodes and magnesium alloys for profiles. As one of the effective methods to prevent metal corrosion, magnesium sacrificial anodes are widely used in underground iron pipelines and petroleum storage tanks for long-distance transportation. As magnesium sacrificial anode, magnesium alloy has a market demand of 30,000 to 40,000 tons/year, and it is growing at a rate of 20% every year.
Magnesium alloy profiles and pipes were previously mainly used in cutting-edge or national defense fields such as aerospace. Due to the improvement of magnesium alloy production capacity and technical level, its production cost has dropped to a level comparable to that of aluminum alloy, which has greatly stimulated its application in civilian fields, such as bicycle racks, wheelchairs, rehabilitation and medical equipment and fitness equipment .
Type
Al-Mg alloy aluminum plate can also be called 5××× series alloy aluminum plate, which represents 5052 aluminum plate, 5005 aluminum plate, 5083 aluminum plate, 5754 aluminum plate, 5A02l aluminum plate, 5A05 Aluminum plate etc. The alloying element of aluminum-magnesium alloy aluminum plate is mainly magnesium, and the magnesium content is between 3-5%. The main features are low density, high tensile strength and high elongation. In the same area, the weight of aluminum-magnesium alloy is lower than other series. Therefore, it is often used in aviation, such as aircraft fuel tanks. It is also widely used in conventional industries. The processing technology is continuous casting and rolling, which belongs to the hot-rolled aluminum plate series, so it can be used for deep oxidation processing. In my country, the 5××× series aluminum plate is one of the more mature aluminum plate series.
1, 5052 aluminum-magnesium alloy aluminum plate: 5052 aluminum plate is an aluminum-magnesium alloy aluminum plate, which is widely used, especially the alloy aluminum plate that is inseparable from the construction industry, and it is also the most promising aluminum alloy plate. The main alloying element of 5052 aluminum strip is magnesium, which has good corrosion resistance, excellent weldability, good cold workability, and medium strength.
5052 aluminum sheet is commonly used in the manufacture of aircraft and automobile fuel tanks, fuel pipes, as well as sheet metal parts of transportation vehicles and ships, instruments, street lamp brackets and rivets, hardware products, electrical enclosures, etc.
2. 5005 aluminum-magnesium alloy aluminum plate: 5005 aluminum plate has the same strength as 3003, good weldability and good workability. 5005 aluminum plate is similar to 3003 alloy, with medium strength and good corrosion resistance. The anodic oxide film is brighter than the oxide film on 3003 alloy and is in harmony with the color tone of 6063 alloy.
5005 aluminum plates are often used as conductors, cookware, instrument panels, shells and architectural decorations, interior and exterior materials for building materials, and vehicle interior materials.
3, 5754 aluminum-magnesium alloy aluminum plate: 5754 aluminum plate alloy has the characteristics of medium strength, good corrosion resistance, weldability and easy processing and forming. It is a typical alloy in Al-Mg alloys. In foreign countries, 5754 aluminum alloy sheets with different heat treatment conditions are the main materials used in the automobile manufacturing industry (car doors, molds, seals) and canning industries.
5754 aluminum plate is widely used in welded structures, storage tanks, pressure vessels, ship structures and offshore facilities, transportation tanks and tanks that require excellent processing performance, excellent corrosion resistance, high fatigue strength, and high performance Weldability and medium static strength occasions.
4. 5083 aluminum-magnesium alloy aluminum plate: 5083 aluminum plate has the highest strength, corrosion resistance and good weldability among non-heat-treated alloys. It is used in occasions that require high corrosion resistance, good weldability and medium strength. The hardness is significantly higher than that of the 5052 series. It is one of the representative products of ultra-hard aluminum plates in the 5000 series.
5083 aluminum plates are often used in ships, ships, vehicle materials, automobile and aircraft plate welding parts, pressure vessels that require strict fire protection, refrigeration devices, TV towers, drilling equipment, transportation equipment, missile components, armor Etc.
5154 aluminum plates are used in welded structures, storage tanks, pressure vessels, ship structures and offshore facilities, and transportation tanks.
5182 aluminum plate is used in thin plates for processing easy-open can lids, automobile body panels, control panels, reinforcements, brackets and other parts.
5252 aluminum plate is used in the manufacture of high-strength decorative parts, such as decorative parts for automobiles. After anodizing, it has a bright and transparent oxide film.
5254 aluminum plate is used in hydrogen peroxide and other chemical product containers.
5356 aluminum plate is used for welding aluminum-magnesium alloy electrodes and wires with magnesium content greater than 3%.
5454 aluminum plates are used in welded structures, pressure vessels, and pipelines for marine facilities.
5456 aluminum plates are used in armor plates, high-strength welded structures, storage tanks, pressure vessels, and ship materials.
5457 aluminum plates are used in decorative parts of automobiles and other equipment that have been polished and anodized.
5652 aluminum plates are used in storage containers for hydrogen peroxide and other chemical products.
5657 aluminum plate is used in the decorative parts of automobiles and other equipment that have been polished and anodized, but in any case, it must be ensured that the material has a fine grain structure.
5A02 aluminum plates are used in aircraft fuel tanks and pipes, welding wires, rivets, and ship structural parts.
5A03 aluminum plate is used in medium-strength welded structures, cold stamped parts, welded containers, welding wires, and can be used to replace 5A02 alloy.
5A05 aluminum plate is used in welded structural parts and aircraft skin frame.
5A06 aluminum plates are used in welded structures, cold forging parts, stressed parts of welded and drawn vessels, and aircraft skin and bone parts.
5A12 aluminum plates are used in welded structural parts and bulletproof decks.
Related information
Surface treatment
As magnesium alloy parts may be in a humid working environment or assembled with other parts of different materials, in order to improve and To ensure the wear resistance, corrosion resistance and visibility of the parts, the magnesium alloy parts must be surface treated. The pretreatment will affect the subsequent spraying. During the manufacturing process, the parts may be contaminated by some contaminants such as grease, oxides, lubricants and foreign matter, and these residual impurities must be removed.
Generally, the pretreatment of magnesium alloy parts can be divided into four categories: mechanical cleaning, solvent cleaning, lye cleaning, and acid cleaning. These methods can be used alone or in combination. Pay attention to the supply of abrasive powder and water during the polishing process, and the polishing should be very bright! AZ91D is more difficult to polish (related to the first few fine sandpapers).
The common surface treatment methods of magnesium alloy parts are roughly divided into: surface coating of oil and wax, chemical treatment, anodizing, spraying, electroplating, chemical nickel, and non-chromium coating.
The performance testing items of magnesium alloy surface treatment include:
Color and appearance, coating thickness and weight, estimation of porous layer, thermal and chemical stability, wear resistance , Corrosion resistance, light resistance and UV light resistance, gloss characteristics, surface density, fracture and flexibility, pencil hardness, grid test adhesion, impact resistance, electrical conductivity and heat transfer, Eriksson Value (Erichsen value), moisture resistance and boiling water resistance, weather resistance, thermal cycle test, chemical resistance (alkali, sulfuric acid, nitric acid, hydrochloric acid, etc.).
Storage and transportation
Mg alloy ingots and die-casting waste must be stored in non-flammable containers, not mixed with other combustibles to avoid moisture. The storage volume should not exceed 1.4m. The height of the stacked storage should not exceed 5.5m, and the sprinkler fire-fighting system cannot be used. The storage channel between magnesium alloys should be at least more than half of the stacking height, and a distance of at least 3m should be maintained. Magnesium ingots should not be placed on flammable floors. Magnesium ingots should not be tilted and should be laid flat. The storage place should have good drainage facilities, and no flammable materials should accumulate nearby.
Mg alloy powder must be stored in a closed non-flammable container, and keep the environment dry. Magnesium alloy powder is easy to produce hydrogen when it meets water, so it must be stored in a covered container with a vent hole and stored in a ventilated environment.