This paper presents the results obtained in a failure analysis study carried out in cast steel railway couplings of the trains of one coal transportation line. A significant number of failures have occurred in these components which led to great losses and disruption of services. The type of failure was mainly fatigue cracking. This paper presents the results from detailed microstructural and fractographic analysis. Strain gauge data were analyzed and from this data fatigue cycles were derived. Cumulative frequency diagrams of stress range and mean stress were obtained and fatigue damage values were calculated. Damage factors were obtained in several zones of the coupling and for the different stages of the journey and loading conditions. Results of a 3D stress analysis obtained with a FE program are presented. The values of the principal and equivalent stresses were obtained in the critical areas of the coupling. Stress concentration factors were calculated from the computed stress distribution and for the critical areas of the coupling.
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