The over view of the advanced manufacturing technology of steel rail
As a practitioner of the railway industry, in addition to the railroad steel price, you will be very concerned about the problem of how rails are made, such as the main components of steel rail, the strength of steel rail and so on. Today, we will talk about the over view of the advanced manufacturing technology of steel rail over the world for all railway enthusiasts.
How Rails are Made?
In the twenty-first century, the railway is still the most effective transportation means to solve the problems of the intercity and city traffic. Especially the high-speed railway and the underground railway, they have huge advantages of high speed, high efficiency safety, comfort, environmental protection and large capacity.
At present, the railway is developing toward the separation of passenger and freight. On the heavy haul railway lines for freight, the full length quenched rails with high strength are adopted by people, which can prolong the service life of the steel rail and improve transportation safety.
On the railway lines for passenger, the full length seamlessly welded rails are popularly used. Due to lighter train axle and faster running speed, the railway track has very strict requirements of smoothness compared to the other railway lines.
Improving the manufacturing precision and original smoothness of the steel rail and increasing the length of track irregularity is fundamental to realize the smoothness. In addition, people need to continue to improve the internal and surface quality of steel rail, improve the strength and toughness of steel rail to fit for the heavy haul railway and high-speed railway. This is the development trend of steel rail.
Main Components of Steel Rail
Carbon is the significantly cheapest and most effective element to enhance the strength and improve the hardness of heavy steel rail. So in the United States, Russia, and Japan, The carbon content of steel rail has been close to that of eutectoid steel. But because the excessive carbon content will destroy the toughness and welding performance of the steel, in Europe and the UK, the low carbon steel is just used on railway lines that don’t need the higher wear resistance.
The alloy steel rails, especially the chromium steel rail, the chromium & molybdenum steel rail, have not only high strength but also good plasticity. Thus, they have been widely in many countries, especially in West Europe. For the 1180MPa tensile strength pearlitic steel rail, due to its poor toughness (less than 25MPa/m2) and bad comprehensive performance, it has been basically dropped out in production. Nowadays, the 1080MPa alloy steel rail is still used in many countries.
The Trend of High Strength Steel Rail Abroad
The hypereutectoid pearlitic steel rail
The eutectoid pearlitic steel rail is made by adding Cr, Mo, and other alloy elements and doing heat treatment to obtain fine pearlitic microstructure in order to improve the performances of wear resistance and hardness. Performance increases at the same time, did not result in railroad steel rail price increases. With the increase of the axle load, the requirements for the wear resistance of steel rail have been further improved. The eutectoid steel has been very difficult to improve the hardness by the above two methods because the surface of railhead will form undesirable brittle bainite and martensite microstructures. In view of the above situations, the researchers put forward a new idea: the hypereutectoid steel can improve wear resistance by increasing the density of cementite phase in lamellar pearlite. Under the laboratory conditions, the wear resistance of hypereutectoid steel can be improved by 20% compared to traditional heat treatment of the eutectoid steel. New developed hypereutectoid steel rail has been tested in North America for heavy haul railway, obtaining very good effects.
The martensite steel rail
Because the pearlite steel rail has been close to the limit based on the research, many manufacturers are testing the other high strength steel rails. Recently, British Steel Union has developed a kind of low carbon martensite steel rail whose hardness has reached up to 445HB. Although the wear resistance of the steel is similar to that of pearlite heat treated rails, the toughness is better.
The bainite steel rail
Currently, the research on new high strength steel rail have been mainly focused on the bainite steel rail in the world. The bainite steel rail has the performances of high strength, good toughness, and good plasticity, showing good cooperation of the strength and toughness. The toughness of the bainite steel rail is 2 to 3 times better than that of the pearlite steel rail. In addition, high strength and toughness of medium and low carbon steel air-cooling bainite rail has good welding performance and is easy to weld with pearlite rail due to its low carbon content.
At present, in the United States and Germany, the bainite steel rail has already been developed out and used on the railway tracks for the related tests. The bainite steel rail developed by Germany has been used on 300m radius curves of the railway line for coal transportation in the north area of Norway. The results show that the wear resistance is 8 times better than that of traditional hot-rolled steel rail. In France and Japan, The bainite steel rail is researched and developed for the purpose of improving the performance of rolling contact fatigue resistance. It has been used on the tracks for the tests. The effect is also good.
From the perspective of prolonging the service life of the rail turnouts, the bainite steel rail is developed in the United States and Britain. More than 1000 sets of turnouts made of the bainite steel have been used with good performance. The bainite steel rail can not only further improve the wear resistance of heavy haul railway tracks but also better the resistance of contact fatigue damage on the high-speed railway tracks. It can reduce the grinding cost of steel rail, at the same time reduce the railroad steel rail price. Meanwhile, it can be used for the production of switch rail and frog, greatly prolonging their service life.
AGICO Group owns rich experience and advanced equipments in railway accessories. We can help you solve the above problems! As professional railway steel rail manufacturers, AGICO Group is major in railway products with good quality such as steel rail, rail fastening systems, rail fishplate, rail tie plate, rail bolt, railroad spikes, steel dog spike, etc. They are exported all over the world. Depending on more than ten years export experience, we can offer the most competitive price and highest quality for our customers all over the world because we are factory. On the other side, we can deal with the international business freely because we have an experienced team in international department. They can offer the best service for our customers. We sincerely seek for reliable cooperators abroad to market the world. Welcome to contact us!
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