Manganese steel is used for making railway tracks because:

Steel is used to make railway rails. This steel must be durable and crack-resistant. This is accomplished by carefully selecting the steel composition and controlling how the hot rail is cooled. Prior to the development of heat treatment processes, the chemical composition of the steel controlled the tensile strength and hardness of naturally cooled rails. Both of these steel properties are affected by the proportion of carbon and manganese. It contains up to 0.82% carbon and 1.7% manganese, which are required to produce hard, wear-resistant rails.