Fatigue crack growth in the D16CzATW aluminium alloy in the presence of a calibrated hole under simple bending

There were examined failure mechanisms in D16CzATW aluminium alloy clad specimens with a notch in the form of a cylindrical hole each. The research was carried out under the conditions of constant-amplitude bending at stress ratio R = −1. As a result of the research, it was concluded that fatigue lives of specimens with calibrated holes were longer by 15–35% (depending on applied loads) in relation to specimens with common holes. The increase was explained by a change in the state of stress around the hole. Significantly bigger differences were observed in comparative tests conducted on similar specimens, clad layers of which had been removed. Reasons for such material behavior were being searched for in research on failure micro-mechanisms conducted with the use of electron microscopy. A negative effect of a plate layer on failure processes was observed.