The density of magnesium alloy is 1.7, which is only 21% of steel and 60% of aluminum alloy. The advantages of lightweight are very obvious. In addition, magnesium alloy has a series of advantages, in the application of bicycles, it has high rigidity and high bending resistance; excellent shock absorption, absorbing shock and vibration. The shock absorption effect of magnesium is 25 times that of aluminum, which makes bicycles better. It has good riding comfort; its high-temperature extrusion molding processability is good, and the thin-wall magnesium alloy pipe fittings are extruded, which significantly reduces the weight of the vehicle; the material is pollution-free, and the secondary recycling is simple. It is a green material.
The important load-bearing structure of a bicycle is the frame. All the components with concentrated overall weight. Therefore, it is necessary to choose machining magnesium alloy frame that is lighter and has good comprehensive mechanical properties to reduce the weight and lightness of the bicycle.
Density, elastic modulus, tensile length, tensile strength, fracture strength, toughness-the mechanical performance parameters of the structural materials required for this series of bicycle frames are divided into equal parts in the magnesium alloy by controlling the trace impurities of magnesium, aluminum, zinc, and manganese. After appropriate forming treatment methods and other measures, its tensile strength and hardness will be correspondingly improved, the strength and elastic modulus will also meet the needs of the frame, and its own high damping coefficient can absorb impact energy and reduce the impact on the rider. Affect and prolong the life of the bicycle.
Because of the excellent performance of magnesium alloys suitable for bicycles, many countries, enterprises and research and development institutions attach great importance to magnesium alloys and their forming technology, and invest a lot of manpower and financial resources in research and development, and very good results have been obtained.
Initially, research and development personnel in many countries used magnesium alloys on a few parts such as handlebars, front forks, and pedals of bicycles. Later, in the research and development process of magnesium alloy bicycle frame, it was discovered that after the deformation process of cross-section change and surface treatment of magnesium alloy, some disadvantages of low magnesium alloy performance were reduced, and its use performance was improved. Therefore, the properties of magnesium alloy materials can meet the needs of bicycle frames, so they have begun to be widely used in bicycle frames, rims, standpipes, gears and other parts.
Advantages of magnesium alloy over other alloys
The bicycle material that Volkswagen riders are most exposed to is aluminum alloy.
The reality is that China’s total aluminum resource ore reserves only account for 2.96% of the world’s total, ranking ninth in the world, and a large amount of imports are needed every year.
According to estimates, according to the current development speed, the domestic aluminum ore resources will be exhausted within about ten years. The long-term dependence on Australia’s imports of aluminum ore also adds uncontrollable factors to domestic supply. Not to mention that the price of imports is firmly in the hands of each other. Once the two countries have political confrontation or the relationship becomes stalemate, they will supply resources. Cause a very big threat. If Australia says that the price is 300 US dollars today and it rises to 700 US dollars tomorrow, China will not be able to bargain because this is a seller’s market.
So what kind of material should we look for to replace when aluminum resources are exhausted? Magnesium is one of the most abundant light metal elements on the earth, and China is one of the countries with the richest magnesium resources in the world. The total reserves of magnesium resource ore account for 21.7% of the world’s total, ranking first in the world and the largest exporter of magnesium resources. Big country.
Comparing the specific strength and specific stiffness of several typical metal structural materials and engineering materials, magnesium alloys are particularly suitable for lightweight structural parts. The elastic modulus is large, the rigidity is good, the shock resistance is strong, the vibration damping performance is 30 times higher than that of aluminum alloy, and the impact load capacity is stronger than that of aluminum alloy. It can be seen that magnesium alloy has excellent mechanical properties.
Die-cast magnesium alloy, like die-cast aluminum alloy and die-cast zinc alloy, has good fluidity; its latent heat of crystallization and thermal conductivity are lower than A380, and its solidification interval is larger than that of A380. Therefore, die-casting magnesium alloy has good filling ability, solidification speed is faster after filling, thermal shock to die-casting mold is small, and it can be used for die-casting thin-walled parts without defects such as hot cracking and under-casting, and reduces die-casting The thermal fatigue phenomenon of the die can prolong the service life of the die-casting die and shorten the retention time of the die-casting parts. The die-casting production rate is about 75% faster than that of aluminum alloy.
Now in the field of bicycle materials, in addition to discussing alloys, it is also discussing carbon fiber. Everyone knows that the strength of carbon fiber is much higher than that of ordinary metals under the same weight, but the relatively high price creates a certain threshold for it.
According to a person in the bicycle manufacturing industry, carbon fiber, after all, has many manual components in the process, and is not as suitable for mass production as magnesium alloy. Therefore, the cost of carbon fiber is relatively large, the time is relatively long, and the requirements for the process are relatively high. These factors directly affect the price of finished products, which makes the most end-users spend more money.
On the other hand, environmental protection is a topic that is valued by all walks of life today, and carbon fiber’s damage to the environment is considerable. A study released by Toyota Motor in 2010 showed that the raw material processing stage of carbon fiber will produce a lot of waste gas and sewage, and the processing process will emit more carbon dioxide. At the same time, its production process may cause various respiratory diseases and skin diseases of workers. sick. After the carbon fiber products are discarded, they will exist in the soil and water for a long time, which is very difficult to degrade, which will further pollute the earth. Therefore, whether carbon fiber is a suitable green material is still unknown.
Magnesium alloys are emerging environmental protection materials in the 21st century, and magnesium alloys are also classified as environmental protection industries abroad. Its performance of environmental pollution-free and recyclable is quite satisfactory.
In addition to the above characteristics, the advantages of magnesium alloys are also reflected in the good heat dissipation and corrosion resistance of organics and alkalis, which are completely different from the characteristics of flammability, self-explosion, instability, and strong activity of pure magnesium.
Advantages of national policy support
In the current “Thirteenth Five-Year Plan”, the state lists magnesium alloy as a very important material, so the guidance and support for this is very strong. For example, for places with large reserves of magnesium resources such as Henan and Shanxi, the state subsidies are very generous. In fact, in addition to the mining of raw materials, as well as in processing, as long as it is related to magnesium alloys, the state will provide a large degree of assistance, with millions of dollars in funds.
“With light weight, high strength, large specifications, high temperature resistance, corrosion resistance, and fatigue resistance as the development direction, the development of high-performance magnesium alloys, focusing on meeting the needs of transportation equipment such as large aircraft and high-speed railways, and accelerating the development of magnesium alloy preparation and deep processing technologies, Carry out application demonstration of magnesium alloys in auto parts, rail trains and other fields.” The “13th Five-Year Development Plan for the New Material Industry” is mentioned in the section.
Link to this article：The Magnesium Alloy Application In Bicycle Frame
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