Railroads have shaped the course of history and industry by changing the way people and goods are transported. The emergence of the mass market in the United States had a major impact on the construction of railroad networks connecting rural areas to distant urban centers. In the era of industrialization and the rise of the mass market, track design and manufacturing no longer used wood, cast iron, or wrought iron. Alloy steels have replaced other materials for the production of medium and heavy-duty structures.
Engineering innovations, metallurgical advances, and improved steel manufacturing processes have standardized the available grades of steel rails. Conformity to standards varies by geographic region. The US, UK, EU, Russia, China, and India have each developed their own standards. Each standard grade is designed to meet specific load-bearing, mechanical, and operational characteristics. Units of measure vary from region to region between metric and imperial, with imperial units still in use in the US and UK.
The steel rail type is customarily expressed by the mass kilogram per meter of rail (kg/m). Chinese rail standards are 75kg/m, 60kg/m, 50kg/m, 43kg/m, 38kg/m, etc. Internationally, there are AREMA, BS, JIS, UIC, DIN, and other standard rails.
The type of rails should be adapted to the volume, allowable speed and axle weight. The choice of rail type should be considered according to the transportation conditions. Technically, it should ensure sufficient strength, toughness, wear resistance, and stability; economically, it should ensure reasonable overhaul cycle and reduce maintenance. The main factors that determine the quality (weight) of the rails:
First, the quality of the rail must match the locomotive axle weight, axle speed ratio is generally above 2.75, increasing the quality of the rail to match the locomotive axle weight;
Secondly, under certain speed conditions, the impact of the wheel on the rail, the vibration of the rail components and the rail bed is inversely proportional to the rail quality. To improve the speed of train operation and ensure the quality of railroad lines, it is necessary to improve the quality of the rails.
Third, the greater the total mass passed, the more likely to cause fatigue damage of rail components and geometric deformation of the rail. Therefore, it is necessary to choose the matching rails according to the annual total mass, so as not to affect the service life of the rails and shorten the maintenance cycle of line maintenance.
Steel rail products are used for a wide range of transportation functions, as outlined below:
Public transportation - passenger railroads, underground railroads, trams.
Freight logistics - bulk material transportation.
Cranes, fixed rail lifting equipment for short and heavy-haul transportation.
Rail damage refers to rail breakage, rail cracks, and other damage that affects and limits the performance of the rail during use. Rail damage is classified into three categories: light injury, serious injury and fracture.
Rail breakage refers to one of the following conditions:
The full section of the rail is broken;
The crack penetrates the entire rail head section;
The crack penetrates the entire rail bottom section;
The allowable speed is not more than 160km/h. The top surface of the section rail has a block with a length greater than 50mm and a depth greater than 10mm.
The allowable speed is greater than 160km/h. The top surface of the section rail has a block with a length greater than 30mm and a depth greater than 5mm.
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