Straight rail is one of the key foundation of railway, and its quality has direct impact on safety production of railway. The rail structure and performance directly determines the quality of the rail track. It is an important guarantee for safe production and operation of high-speed railway.
High-speed railway is an important means of transportation. It adopts the rail structure of main line and the special steel (strength) specification. The special steel rail should have the following performance:
1. Wear Resistance. With the support of the locomotive wheels, the rail can bear the pressure of the entire train. During the running process, the pressure caused by the drive wheels coming in and out must be very large. This requires that the rail has good wear resistance to ensure the safe and smooth operation of the train.
2. Strength and toughness. The running speed of the high-speed railway is very high. The train runs at a high speed and the track must have good strength to resist the strong impact of the train speed. The rail steel must have high strength and toughness, in order to have the necessary resistance pressure of high-speed rail.
3. Corrosion resistance. As the track is open air exposed to the environment and contacting with water, so the rail needs to have good corrosion resistance, which ensures that the rail will not corrode and can work as normal.
4. Fatigue resistance. With the increase of the train speed, the shock on the track will gradually increase. The rail should have strong fatigue resistance to avoid crack of the rail caused by fatigue, affecting the safety of the train running.
The high-speed railway adopts the steel rail with a special steel grade and specification. The steel grade of the rail is mainly Q235, which is made of three elements, such as carbon, silicon, manganese and other elements, as well as control of mechanical properties. Thirdly, the surface quality of the rail is required to be high and the allowable has slight burrs.
The steel rail required for the high-speed railway is mainly 600MPa or above in terms of tensile strength and 30000MPa in terms of yield strength. The impact toughness is not less than 31 J/cm, and the surface quality is required to meet the corresponding standard.
The steel composition of the high-speed rail steel is different from that of the ordinary rail steel. The high-speed rail steel mainly contains high content of alloy elements, such as alloying elements, strengthening elements and certain amounts of special elements. Alloying elements mainly contain 63%Ni. The corresponding content of special element V is 0.0045-0.005%. The alloying element of high-speed rail steel can make the steel structure homogeneous and optimize the carbide distribution of the steel. In this way, the steel can achieve the corresponding strength and toughness when the steel is cooled from high temperature.
In summary, with the characteristics of wear resistance, strength, toughness, corrosion resistance, fatigue resistance, high speed rail steel has good performance. Steel material is a kind of important basis for ensuring the safe and smooth operation of railway, and its performance quality directly affects the quality of infrastructure, which is of great significance to the transportation of Chinese high-speed railway.
