Railway parts fatigue behaviour under influence of the inner imperfections

Abstract

Contribution is devoted to the study of cracking of cast railway frog. In contribution are summarized of findings that were found during investigation of source of cracking. Material properties were investigated by mechanical properties of materials. Fracture area was study by macro and microstructure (fractography) and microstructure and structure defects of bulk material was study by optic and SEM microscopy. Initialization of crack was found in synergic incidence of initial heat cracks and stress concentration in sizable change of cross-section of cast. Main source of failure was found in technology of heat treatment of cast and/or not very proper design of cast.