The study investigates the mechanical properties and fatigue behavior of steering knuckles used on commercial vehicles. The steering knuckle is made of hot forged bainitic steel, which is known to show high levels of strength, toughness, and hardness. The local strain concept was adopted to assess the cyclic behavior of the axle stub based on the stabilized cyclic material parameters using the Ramberg-Osgood equation. For this purpose, experimental investigations have been conducted on both the steering knuckle as well as fatigue specimens under constant and variable amplitude loadings. The fatigue specimens were removed from the area next to the crack initiation location, to represent the microstructure in the critical area of the component. Finite element models of the steering knuckle and the specimens were examined in more detail using ABAQUS software to determine the local equivalent stress/strain (Von Mises) values in the critical areas. For this purpose, a mesh convergence study was performed on the FE models to ensure the accuracy of the solution. Furthermore, the influence of the size effect (notch factor, stress gradient, highly stressed volume HBV90, surface roughness) on the fatigue strength of the component was also taken into consideration for the assessment.