Effects of Cold Expansion on Residual Stress of 7050 Aluminium Alloy Frame Forging

Abstract

Regulation of residual stress in a component is the key to improving its service performance. A cold expansion method was proposed for reducing the residual stress in 7050 aluminium alloy curved frame forging after quenching. The effect of the cold expansion method on the residual stress and equivalent plastic strain distribution of the 7050 aluminium alloy curved frame forging was investigated. The results showed that the maximum residual stress at the center thickness was reduced from 153 MPa to 94 MPa after the cold expansion, while it decreased from 283 MPa to 120 MPa at the surface with the highest stress reduction rate of 86.2%. The stress uniformity in the final forming region of the forging was improved. The equivalent plastic strain of the forging gradually decreases from the center to each side along the diameter of the expanded hole in cold expansion. The stress reduction effect matched with the distribution of equivalent plastic strain. The surface stress of the forging measured by x-rays diffraction (XRD) method was in agreement with the simulation results, and the reliability of the numerical model was verified. The cold expansion method can effectively reduce the quenched residual stress in curved frame forging.

Numerical Simulation and Experiment of Stress Relief and Processing Deformation of 2219 Aluminum Alloy Ring

“…In the ring rolling process, the blank forming process inevitably generates high and uneven residual stress. Research by experts [7] suggests that the decrease in peak residual stress changes the internal stress field, causing the internal stress of the component to decrease and redistribute, achieving equilibrium at lower stress levels. Therefore, after the ring blank forming process, aging techniques (such as natural aging, TSR, VSR, and TVSR) are generally used to eliminate or reduce the adverse effects of residual stress on the workpiece.…”