Experimental study on fatigue crack growth of QSTE420TM steel with a single dwell-overload and a combined prediction model

To study the fatigue crack behaviors of QSTE420TM steel under constant amplitude with a single dwell-overload, a series of experiments are performed. The dwell time changed from 0 s to 106 s. The result shows that the dwell-overload retardation is more distinct than the single overload. The retardation degree is not proportional with the dwell time, its greatest level appears when the dwell time lasted 104s, then it gradually becomes stable. A combined model, which considers the effects of both residual stress and crack closure, is proposed by introducing a dwell factor to describe the plastic zone at the crack tip. [Display omitted] •The tests were conducted on QSTE420TM steel with a single dwell-overload.•The retardation phenomenon under dwell-overload is more obvious than overload.•A time-dependent model considering the residual stress effect and crack closure effect was proposed.•The model is able to predict fatigue crack growth rates and lifetimes well.