Impact of continuous temperature variations on the strength of railway line steel

Abstract

This research focuses on the impact of temperature variations on the mechanical properties of railway line steel. Railway line steel must be made from a strong material that endures wear, fatigue, and various temperature effects in order for the railway transport to supply an uninterrupted service of goods to customers. The mechanical properties of the structural materials strongly depend on their microstructure. The fatigue tests were conducted, and repeated linear load tests were applied to check the behaviour of the material. The reports released by the Railway Safety Regulator in South Africa 2017 reveal many defects found on the railway lines, and it cannot at this point be determined how they develop to the state of disturbing the transport service. Many researchers agree that temperature can have an impact on the steel, but it is not yet clear how temperature can affect the material properties of railway line steel. This research has discovered that temperature has an effect on mechanical properties of the steel. The microstructure results have shown that fatigue load causes microstructure grain transformation, dislocating element grains. The results have shown that as the temperature increases due to repeated cycle loading, carbon content decreases, so the steel hardens increased to 443.3 HV0.5. It is assumed that crack defects develop on the areas where brittleness has become the highest. Further research is needed to effectively evaluate and compare a sample which has been in use and a virgin sample to see the actual appearance of the microstructure results of both, this will help in defining the maximum lifetime of the rail steel and to know when it can be replaced.