Influence of Inclusion on Crack Initiation in Wheel Rim

Speed increase and heavy haul of the railway freight car are the effective measures to raise the transport ability of railway, and they have been the new trend for railway freight car development. The increase of speed and axle load will lead to the increase of wheel-rail contact stress, which will make a great change of stress distribution in the whole wheel rim. Goodier equation was employed to analyze the stress state around inclusion and cavity. In the operation of wheel-rail contact stress, stress concentration occurred in the pole of Al2O3 spherical inclusion, while it appeared on the equator of cavity. The critical inclusion sizes of 250 kN axle load freight car wheel at different velocities, a certain distance away from the tread, were calculated by Murakami equation. Comparing the inclusion in cast steel wheel with that in rolled steel wheel, it is found that the inclusion in cast steel wheel has much more excellent crack resistance than that in rolled steel wheel. In the meantime, in order to reduce the probability of rim crack, some suggestions were put forward.