Effect of Pro-eutectoid Cementite on Fatigue Crack Growth Behavior of Pearlitic Steels

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 surface more frequently contained islanded brittle surfaces than other steels. In steel, total area fraction notably increased with an enhancement maximum (Kmax) due extension. More detailed SEM fractographies were performed comparing between before after etching order identify microstructures beneath appearances steel. As results, it suggested θ involved formation fracture. Based these investigations, hyper-eutectoid discussed terms static induced by near tip.