Types and Applications of National Standard Rails
- What are the common types of national standard rails?
Common types are classified by approximate mass per meter, including 43kg/m, 50kg/m, 60kg/m, 75kg/m, etc. In terms of material, there are carbon rails, micro - alloyed rails and low - alloy rails. For example, U71Mn belongs to carbon rails and is widely used in ordinary lines; U75V is a micro - alloyed rail. The addition of vanadium element improves its strength and toughness, making it suitable for heavy - haul lines.
- How to distinguish the application scenarios of different types of national standard rails?
43kg/m rails are generally used in branch railways or lines with small traffic volume due to their relatively low bearing capacity. 50kg/m and 60kg/m rails are widely used. 50kg/m is often used in existing ordinary trunk railways, and 60kg/m is a common choice for newly built ordinary trunk lines and some passenger dedicated lines. 75kg/m rails have high strength and are mainly suitable for heavy - haul railways, which can bear large axle loads and traffic volumes.
- How does the material of national standard rails affect their performance?
Carbon rails have lower costs and mature processes, but their strength and wear resistance are relatively limited. Micro - alloyed rails refine grains and improve strength, toughness and fatigue resistance by adding elements such as vanadium and titanium. Low - alloy rails add a small amount of alloy, such as EN320Cr containing chromium, which has excellent wear - resistance and corrosion - resistance and is suitable for harsh environments or highly worn lines.
- How to select the appropriate type of national standard rails?
It is necessary to comprehensively consider factors such as line purpose, traffic volume, axle load and driving speed. Passenger dedicated lines require good ride comfort and mostly select high - quality rails of 60kg/m and above; heavy - haul railways, due to large axle loads and traffic volumes, should choose 75kg/m rails with high strength or rails of special materials; branch railways or lines with small traffic volumes can select 43kg/m or 50kg/m rails according to cost and demand.
- What are the standard lengths of national standard rails? What impact does it have on laying construction?
In terms of standard lengths, the length of 43kg/m is 12.5m or 25m; the length of rails above 50kg/m is 25m, 50m, 100m. Seamless lines often use 100m rails (hundred - meter fixed - length rails) produced by steel mills, which are welded into 500m long rails in the rail welding factory and then welded into the required length on - site at the construction site. Longer rails can reduce the number of joints, reduce the impact and vibration during train operation, and improve the smoothness of the line. However, they require higher technical and equipment requirements for laying construction. For example, professional welding equipment and processes are needed to ensure the welding quality.