Influence of plastic deformation in fatigue crack behavior in bainitic steel

Abstract

In the present paper, the behavior of fatigue microcracks is studied in a high-strength bainitic steel with the aim of identifying the microstructural features that influence the mode of initiation and propagation of microcracks. For this study, a gradual monitoring of surface damage during low-cycle fatigue test at different plastic strain ranges was carried out by means of light optical and electron microscopy along with EBSD data analysis. Moreover, the dislocation structure near the surface was analyzed and correlated with the crack initiation site. The results showed a change with respect to cracking mechanisms from 0.2% plastic strain.