Abstract
•HCF behavior between bainitic and ferritic-pearlitic forging steels was compared.•Fatigue strength is a power function of stress concentration factor.•A simple method for predicting notched fatigue strength of components is proposed.•Bainitic steel shows better notched fatigue properties of the two tested steels.•Bainitic steel is a promising candidate to manufacture auto security components.
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.