Effect of cutting speed and tool rake angle on the fatigue life of 2024-T351 aluminium alloy

Ring-shaped specimens of 2054-T351 aluminium alloy were machined orthogonally on a lathe equipped with a quick-stop device at cutting speeds of 0.5–1.5 m s^?1 with tools having positive rake angles in the range 10–30°. The machined specimens were then fatigued at a selected stress and the resulting fatigue lives were compared with that of the virgin material. The surfaces of the specimens were examined using optical and scanning electron microscopy.The fatigue life of the machined specimens was found to increase with increasing cutting speed or tool rake angle. The fatigue life of the specimens machined at higher cutting speeds was higher than that of the virgin material, due to the presence of compressive residual stresses in the surface layers. At lower cutting speeds the surface damage was so severe that, in spite of the presence of compressive residual stresses in the surface layers, the fatigue life of the machined specimens was lower than that of the virgin material.