Different rail types and operating conditions around the world
Railways rails - Metallurgical aspects

The rail is a rolled product of pearlitic steel (carbon content between 0.5 and 0.85%) with HB (Brinell hardness) hardness ranging from 200 to 440, with or without the addition of alloying elements and with or without heat treatment, having a rolled structure with an index grain of 7 to 9, corresponding to an average grain diameter of between 18 and 36 μm.

Geometrically, it consists of a massive "mushroom" tread at the top, up to 75 mm wide, with a transverse radius of 300 mm on the central major part, completed by two symmetrical radii of 80 mm and then 13 mm in connection with the vertical walls (figure 1). This quasi-horizontal surface supports all rail-wheel contact stresses (Hertz stresses).