Damage behavior of heavy-haul rail steels used from the mild conditions to harsh conditions

Abstract

Systematic experimental investigations were conducted to study the damage behavior of rail steels with eutectoid and hypereutectoid microstructure under different axle load and curve radius conditions. The wear resistance and resulting failure mechanism, as well as subsurface crack development were evaluated by wheel/rail rolling contact test rig, which can realize a broad range of working conditions from mild condition to harsh condition. Results demonstrate that the wear resistance and rolling contact fatigue (RCF) damage depend on not only the working conditions employed, but also the microstructures. With the increase of axle load and reduction of curve radius, the wear rate increases for both rail steels. Damage mechanisms for the two rail materials are mainly surface fatigue cracks and delamination, which become much serious from the mild condition to harsh condition. The hypereutectoid rail possesses a better wear resistance than eutectoid rail in general. Wear regime map suggests that the hypereutectoid rail did not have a catastrophic wear region, but can be observed in eutectoid rail. The subsurface analysis shows that the working condition has a significant impact on surface crack development depending on specific microstructure types. The hypereutectoid rail is more suitable for harsh working conditions than eutectoid rail.