FATIGUE BEHAVIOR OF A RAIL STEEL

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Abstract
The fatigue behavior of a hot‐rolled, control‐cooled, plain carbon eutectoid rail steel has been characterized. The data include monotonic and cyclic stress‐strain curves, low cycle fatigue data and near‐threshold fatigue crack growth rate behavior in air and in vacuo. The effects of environment and mean stress on the near‐threshold fatigue crack growth rates of rail steel are significant. At a low stress ratio (R), ΔKo is lower in vacuum (7 MPa √m) than in moist air (10 MPa √m). At high R, ΔKo is higher in vacuum (6 MPa √m) than in air (4 MPa √m). The beneficial effect of moist air on FCGR at low ΔK and low R is attributed to an increase in closure due to fracture surface roughness and oxide film.