Experimental Study and Numerical Simulation on Fatigue Crack Growth Behavior of GH4133B Superalloy

摘要

The fatigue crack growth tests for GH4133B superalloy are carried out at room temperature. The stress intensity factor ranges and the fatigue crack growth rates at various stress ratios are tested, and the corresponding threshold stress intensity factor ranges are measured. Using the Paris formula, the experiment data of fatigue crack growth are analyzed. It is shown that the fatigue crack growth rate increasing with increasing stress intensity factor range and stress ratio, and a modified Paris formula considering threshold stress intensity factor range can well describe the fatigue crack growth behavior. The fracture surface morphologies are investigated using a scanning electron microscope. It is shown that in the crack initiation region, steady growth region and rapid growth region, the fracture surface exhibits a cleavage fracture mode, fatigue striations and an intergranular fracture mode, respectively. Finally, the von Mises stresses and stress intensity factors at the crack tip of specimen of GH4133B superalloy at various external loads and crack lengths are simulated using the finite element method, and the threshold stress intensity factors under different maximal external loads at a certain crack length are calculated. The comparison between test and simulation indicates that the stress intensity factors at the crack tip calculated by the finite element method agree well with experimental data.