Experimental study and examination of failure zone factors and causes of destruction of thick metal sheets of rail cranes: mechanical properties, chemical analysis and metallography

In this research, several samples of thick sheet metal from the fracture area and its surroundings related to a crane have been examined and studied in order to investigate the causes of destruction in this research. The studied sample is related to a German-made rail crane that was built in 1974. In order to investigate the causes of destruction, first the fracture surface and the external surface of the sample were studied by a stereo microscope. Then, the chemical analysis of the sample was determined by the emission spectroscopy method. In order to investigate the microstructure, metallographic samples were prepared from a cross section and studied by an optical microscope. To determine the mechanical properties, hardness and tensile tests were performed at ambient temperature. To complete the studies, the fracture surface was examined by scanning electron microscope. Based on the studies conducted and the results obtained from the experiments, the main cause of failure is fatigue corrosion. Relatively deep corrosion pits on the surface along with surface cracks in the uncovered areas indicate the occurrence of corrosion, which has led to failure by considering the service time, the presence of working stresses (mainly cyclical) and overload conditions at certain times.