Study on fatigue property of a new 2.8 GPa grade maraging steel

A new 2.8 GPa grade maraging steel was developed in the present work and the tension–tension fatigue property of the steel was studied after peak-aging treatment. The results showed that the steel could reach an ultimate tensile strength of 2760 MPa, a fracture toughness of 31.6 MPa m1/2, and a fatigue limit of 1150 MPa at stress ratio of 0.1. It was revealed that the fatigue crack initiation of the steel mainly originated from the surface at high stress level but from the interior inclusions at low stress level. From the observations by transmission electron microscope (TEM) and fatigue crack propagation curves, it was proposed that the cyclic softening occurred, which was induced by the resolution as well as the growth of precipitates, and the poor fatigue crack growth resistance and high fatigue crack propagation rate might be the main reason for the relatively low fatigue limit of the steel.