An Investigation on Rotating Bending Fatigue Behavior of Nanostructured Low-Temperature Bainitic Steel

The aim of this work is to investigate the fatigue behavior of a new class of nanostructured, low-temperature bainitic steels, where rotating bending fatigue tests were conducted on samples isothermally transformed at 300, 250, and 200 degrees C, after which, fracture surfaces were examined using scanning electron microscopy. Results showed that, fatigue limits of about 820, 945, and 1,005 MPa were achieved for the samples transformed at each transformation temperature, respectively. Moreover, according to the SEM micrographs, secondary crack initiation was observed in the high carbon retained austenite blocks for samples transformed at 300 degrees C and at the interface of blocky austenite-bainitic ferrite for samples transformed at 250 and 200 degrees C.