Hardness Standard Of Railway Rails

Rails are the main components of railway tracks. Their function is to guide the wheels of locomotives and vehicles forward, bear the huge pressure of the wheels, and transmit it to the sleepers. Rails must provide a continuous, smooth and least resistant rolling surface for the wheels. In electrified railways or automatic block sections, rails can also serve as track circuits.

For ordinary carbon steel rails, such as the common U71Mn rails, the surface hardness of the rail head is generally required to be 260-300HBW (Brinell hardness). After heat treatment and other processes, the surface hardness of the rail head can be increased to 330-380HBW to enhance the wear resistance and fatigue resistance of the rails and meet the growing demand for railway transportation.

In high-speed railways and heavy-duty railways with high line speeds and large axle weights, alloy steel rails such as U75V are used, and the surface hardness of the rail head is usually required to reach 350-400HBW. For example, the rail head hardness of some high-speed railway rails in my country with a speed of 350km/h is strictly controlled within this range to ensure that the rails can still maintain good service performance under the frequent impact and friction of high-speed trains and reduce the occurrence of damage and injury.

The turnout point rail has more stringent hardness requirements due to its complex working conditions and frequent impact and sliding friction from trains. Generally, the surface hardness of the point rail head must reach 380-450HBW. For example, the surface hardness of the high manganese steel cast frog, the heart rail and the wing rail should not be less than 200HBW in the cast state. After heat treatment, the working surface hardness of the heart rail can reach 380-450HBW to ensure the stability and reliability of the turnout when trains pass frequently.