Effect of surface integrity on fatigue life of 2024 aluminum alloy subjected to turning

Changes in cutting parameters can cause changes in surface integrity and affect fatigue life. In this paper, the surface integrity and fatigue life of 2024 aluminum alloy were studied by surface integrity measurement, tensile fatigue test and fatigue fracture characterization with cutting speed and feed rate as control variables. The main factors affecting surface integrity and fatigue life were analyzed, and a fatigue life prediction model considering fracture surface roughness was proposed. Finally, the mapping relationship between surface integrity and fatigue life was established. The results showed that the feed rate contributes the most to the surface residual stress (σ_rs) and surface morphology (R_aR_y/R_z), and the surface residual stress (σ_rs) contributes the most to the fatigue life. The prediction accuracy of the fatigue life prediction model considering the fracture surface roughness is as high as 99 %. At the same time, Murakami equation can well explain the initiation and propagation mechanism of fatigue cracks. The increase of feed rate will increase the fatigue life, while the increase of cutting speed will reduce the fatigue life.