Estimation of the strength and crack resistance of the metal of railway wheels after long-term operation

We describe the results of investigations of the state of the metal near the roll surfaces of solid-rolled railway wheels after operation. It is shown that the greatest changes in structure (phase components, grain, subgrain, and dislocation structures, phase precipitates, etc.) over the width of the working surface of wheels take place in the zone of passage to the flange and propagate to a depth of up to 200 to 300 μm (from the roll surface). The analytical estimate of changes in the strength and crack-resistance properties of the metal in different zones of railway wheels, based on the results of structural examinations, enabled us to establish that separate zones are characterized by a substantial strengthening of the near-surface layers, a dramatic increase in the local internal stresses up to the value of theoretical strength, and, correspondingly, a decrease in crack resistance.