High cycle fatigue behavior of V-microalloyed medium carbon steels: A comparison between bainitic and ferritic-pearlitic microstructures

High cycle fatigue behavior of two V-microalloyed medium carbon steels with ferritic-pearlitic and bainitic microstructures were studied by using rotating bending fatigue and fatigue crack growth (FCG) testing. The results show that fatigue strength σw is a power function of Kt with its coefficient equals to smooth fatigue strength. This function provides a simple method for predicting notch fatigue strength of components. Bainitic steel shows higher σw, lower fatigue notch sensitivity and FCG rate than those of ferritic-pearlitic steel. It is concluded that bainitic steel is a promising candidate to manufacture automobile security components in terms of fatigue properties.