Abstract: In order to explore the influence law of quenching residual stress on the fatigue crack propagation of the aluminum alloy thick plate, a numerical simulation model of three-dimensional crack on 7075 aluminum alloy plate was developed. The method of sequentially coupled thermal-stress was used to solve the quenching residual stress field, and the residual stress field was taken as the initial load condition to solve the stress intensity factors of the crack, then compared it with the value of stress intensity factors without residual stress field. Under these two conditions, the distribution of stress intensity factors and their similarities and differences were studied. By analyzing the evolution curve of crack stress intensity factors along with the crack position angle under different uniform tensile stress loading in different crack radius with initial quenching residual stress, the influence law of the quenching residual stress on crack propagation trend was found out. The results show that the existence of quenching residual stress changes the distribution of stress intensity factors and crack propagation trend of the aluminum alloy thick plate, and the crack propagation near the surface is restrained by quenching residual stress.The crack tends to propagate preferentially in the thickness direction.

Key words: quenching residual stress, aluminum alloy, stress intensity factors, crack propagation