Effect of secondary banded structure on the fatigue properties of non-quenched and tempered micro-alloyed steel

The effect of banded structure on the fatigue properties of DG20 Mn and 35 Cr Mo micro-alloyed steels was investigated by using axial tensile fatigue tests at a stress ratio of 0.1. The results show that secondary banded structure has no significant effect on the axial tensile properties of the tested steels and the axial tensile fatigue performance of 35 CrMo steel,but decreases the axial tensile fatigue performance of DG20 Mn steel. Under the high cyclic tensile stress,multi-source damage cracks in the steels initiated by secondary banded structure,which changes the fracture mode,is the major factor of the decrease in fatigue life of the steels.