Rails generally do not have a homogeneous austenite grain structure across their sections because the degree of plastic strain achieved during hot-rolling depends on location.Here we explore a philosophy in which niobium microalloying may be introduced in order to thermomechanically process the material so that pancaked and refined austenite grains may eventually be achieved in the critical regions of the rail.The essential principle in alloy design involves the avoidance of coarse niobium carbide precipitates in the regions of the steel that contain chemical segregation caused by non-equilibrium solidification.Both pearlitic and cementite-free bainitic rails have been studied.The work is of generic value to the design of high-carbon microalloyed steels.