Fatigue crack propagation behavior in dual-phase steel

The fatigue crack propagation in dual-phase steel was studied with the objective of developing ferriticmartensitic microstructures via intercritical annealing and thermomechanical processing. It was found that the changes in fatigue crack propagation rates and in the threshold stress intensity range, ΔKth, resulting from microstructural variations, were directly related to tensile strength in the same manner that was observed in other types of structural steels. It was also observed that the relationship between tensile strength and fatigue crack propagation in intercritically annealed and thermomechanically processed dual-phase steel was much the same as for conventional steels of similar strength level.