Rails and Rail Steel

Rails and Rail Steel Rail steel is used to make rails for railway lines and for other uses such as tracks for moving equipments like cranes, transfer cars etc. Heavier rails carry heavier and faster trains on the tracks. The rails represent a substantial fraction of the cost of a railway track. Worn, heavy rail from a mainline is often reclaimed and downgraded for re-use on a branch line, siding or yard or rerolled in rerolling mills to produce other steel products. Rail steel is hot rolled steel of a specific cross sectional profile (an asymmetrical I- beam) designed for use as the fundamental component of railway track. The rail profile is the cross sectional shape of the rail perpendicular to the length of the rail (Fig 1). Fig 1 Typical cross section of a rail The importance of the rail steel can be known from the fact that even after years of service and high stress, there is no difference between the grain structure of a used rail and a new rail. Age, traffic and weather do not change its basic properties. All stresses are relieved through heating in the used rail prior to being rerolled. This rerolling decreases the grain size of the used rail steel and hence improves its resiliency. History Earlier wooden rails were used on horse drawn wagon ways.  By 1760s strap iron rails, which consisted of thin strips of cast iron fixed onto wooden rails came into use. These were superseded by cast iron rails that were flanged (i.e. ‘L’ shaped) and with the wagon wheels flat. In 1789, the edge rails where the wheels were flanged were introduced and, over time it was realized that this combination worked better. The earliest of this in general use were...