Effect of temperature on the performance of railroad wheels

Abstract

Sliding and tread brake heating are known to alter microstructures and properties and show causal relationships with shelling and spalling. Temperature can also affect the performance of wheels in other ways: rolling contact forces depend on the size of the contact patch, which is affected by the elastic modulus, which in turn is affected by the tread temperature. Temperature differences from the rim to the remaining portion of the wheel may cause distortions, which may result in unfavorable contact between the wheel and the rail. Cold temperatures affect the fracture toughness and, in the presence of water, may cause wedging, which will accelerate the shelling process. Oxidation within a crack can also cause wedging, resulting in the propagation of thermal cracks. Changes in the residual stress due to brake heating can also affect shakedown. This study considers the many ways of how temperature can affect the performance of the railroad wheel of a freight car. Most of the author’s observations relate to the freight car service in North America and may not be applicable to other types of service in other parts of the world.