Study of the fatigue fractography of dual phase low carbon steel used in automotive industry

• The highest fatigue strength was obtained for samples quenched at higher temperatures. • Different topography is found for each level of stress. • Different failure mechanisms depending on the level of stresses. Fatigue properties play a crucial role as they are vital to ensuring the durability and integrity of components subjected to repeated loading conditions over long periods. The main objective of this work is to investigate the fatigue behavior of dual phase low-carbon steels used in automotive applications using a rotating bending fatigue machine. Heat treatments were carried out to analyze the microstructure's effect on the fatigue properties, including quenching low-carbon steel samples at 800 °C and 900 °C. Hardness and tensile tests were performed, and the microstructure was inspected to examine the constitute phases. With the assistance of a scanning electron microscope, fractographic analyses were carried out to reveal the fracture features of the samples at different lifetime ranges. The results show that various failure mechanisms occur depending on the stress levels. Additionally, the specimens quenched at 900 °C exhibited higher fatigue strength.