A study of fatigue crack growth rate was conducted in two pearlitic rail steels, namely R260 and R370CrHT. Two crack plane orientations with respect to the rolling direction were tested and separate experiments were performed to cover a wide variation in fatigue crack growth, from the fatigue threshold (circa 10 (9) m/cycle) to rapid fracture conditions. The fracture surfaces were examined and some correlations between microstructural features such as interlamellar spacing and mechanical properties were made. (C) 2015 Elsevier Ltd. All rights reserved.138 6372Brazilian Nanotechnology National Laboratory (LNNano, Campinas)Medellin City Hall with his program "Enlazamundos"Colciencias