Fatigue and fracture behavior of pearlitic Grade 900A steel used in railway applications

• The damage tolerance performance of a Grade 900A rail steel has been investigated.
• Compared to other pearlitic rail steels.
• The material exhibits high fatigue resistance with a high fatigue limit.
• The steel exhibits low fracture toughness and cleavage-type fracture characteristics.
• Fatigue crack growth resistance is moderate under positive stress ratios.

In overloaded railway networks, rail surface defects developed under rolling contact fatigue (RCF) if left untreated, may propagate to the bulk of the rail and become critical for its structural integrity. To avoid critical situations, the fatigue and damage tolerance behavior of railway steels is of high importance. In this experimental study, the fatigue and fracture performance of a pearlitic Grade 900A rail steel, which is used in the railway network of Attiko Metro in Athens has been investigated. The rail material is an annealed steel with pearlitic microstructure, combining high strength with a high strain hardening rate and excellent high cycle fatigue behavior. On the other hand, the material exhibits brittle fracture characteristics with inferior fracture toughness and fatigue crack growth resistance compared to other pearlitic rail steels. The mechanical performance suggests that the material resists crack initiation, but for application purposes maintenance schedules should be able to identify fatigue cracks at early stages to avoid propagation of cracks to critical lengths compromising structural integrity.