The application fields of magnesium alloys. Currently, there is nearly 1 million tons of magnesium and magnesium alloys produced, although it is significantly less than the production of aluminum alloys. However, magnesium alloys have been widely applied in areas such as lightweighting, medical care, and mineral smelting. As the lightest metal material, the application of magnesium alloys can enhance transportation efficiency, increase train running speed, and contribute to the realization of energy-saving and green development goals.
Market Background of Rail Transit Vehicles and Application of New Materials
Railway vehicles include high-speed railways, medium-low speed maglev lines, subways, elevated urban rail systems, metropolitan rapid rail systems, intercity express railways, urban monorail systems and maglev vehicles, etc. They continue the technological progress path of high-speed, heavy-load and electrification over the past half century, promoting significant evolution and transformation of the urban forms in global metropolitan areas.
In the new development era, concepts such as green, environmental protection, intelligence, and sustainability have raised public expectations for the safety, comfort, environmental friendliness, and reliability of rail transit systems. Traditional structural car bodies made of metal materials are facing numerous performance challenges in complex and variable service environments such as high altitudes, deserts, high temperatures, extreme cold, and high altitudes. Therefore, it is necessary to continuously absorb and utilize advanced scientific and technological achievements, including material sustainability, to continuously improve the construction and operation levels of rail transit projects. The diversification of materials is the main way to achieve a balance in the performance of rail transit (strength, vibration, noise, insulation, radiation).
The application of magnesium alloys in the field of rail transportation
Research is currently underway on shorter-length empty railway passenger car bodies. For longer-length subway train and other vehicle models, there have been application achievements only in non-primary load-bearing components such as air conditioning ventilation grilles, window guardrails, seats and floors, berth bed frames and supports, luggage rack frames, and internal instrument panel frames. There are relatively fewer achievements in the car body aspect.
The ICE high-speed trains of German Siemens, the N700 series high-speed trains of Japan's Shinkansen, the KTX express trains of South Korea, and the TGVDuplex double-decker high-speed trains of France all adopt magnesium alloy components such as seats, small tables, handrails, steps, and the sides of seats. Compared with traditional aluminum alloy seats, each double-person seat weighs 6 kg less, accounting for 1/5 of the total weight, and also reduces the material cost by 8% to 10%.
The problems and development of magnesium alloys' application in rail transit fields
Magnesium alloys possess both flame-retardant properties and high strength and toughness: A series of high-strength magnesium alloys have been developed, and the mechanical properties of some of these alloys can reach or even exceed those of aluminum alloys.
However, the ignition point of traditional magnesium alloys is around 650-700℃, which is insufficient to be applied in the key components of rail transit vehicles. Currently, a series of magnesium alloy systems containing Ca and RE have been developed. Compared with traditional magnesium alloys, the ignition point of these alloys can be increased by 200-300℃.
How to develop a high-strength and flame-retardant structural-functional integrated magnesium alloy material is the future research and development focus.