Effect of overloads on fatigue crack propagation within molded parts of railroad constructions

To determine the regularity of fatigue crack propagation during cyclic loading with tensile overloads, a method of the estimation of the effective stress ratio of loading cycles, which is equivalent to the rate of crack propagation by the diagram of fatigue failure, is proposed. Thereby, the relation between the diagram of the fatigue failure and the phenomenon of crack retardation after tensile loads, which is complicated by its physical nature, is established. The experimental-computational studies were carried out on 20гΦЛ steel of a bogie bolster of a freight car.