Effect of retained austenite characteristics on fatigue behavior and tensile properties of transformation induced plasticity steel

Highlights: → Fatigue behavior studied in C-Mn-Si TRIP steel. → Amount of retained austenite and its stability is an important factor. → By increasing retained austenite phase, the fatigue life of TRIP steel increases. → Transformation of retained austenite to martensite during cyclic loading affects fatigue crack propagation. → More cycling load need for fatigue failure of TRIP steel with stable retained austenite. -- Abstract: Transformation induced plasticity steels are commonly used for automotive industry due to their high strength and high ductility. These steels achieve good balance of strength and ductility due to transformation of retained austenite to martensite during deformation. In this study, effect of retained austenite characteristics on fatigue and tensile property of conventional CMnSi steel is evaluated. Tensile and fatigue test were carried out at room temperature. After mechanical tests, fractography observations were carried out by scanning electron microscopy. All samples show reasonably high values of tensile strength and fatigue limit. Results of fatigue test show that fatigue performance of this steel improved by increasing volume fracture of retained austenite.