The influence of pro-eutectoid cementite on fatigue crack growth behavior was investigated using various pearlitic steels containing from 0.64 to 1.21 mass%C. rates the hypo-eutectoid and eutectoid hardly changed, while that mass%C steel having a large amount (θ) accelerated especially in high stress intensity factor region. Scanning electron microscope (SEM) observation revealed fracture surfa...