Laser-ultrasonic measurements of residual stresses in a 7075-T651 aluminum sample surface-treated with low plasticity burnishing

Low-plasticity burnishing (LPB) is used to introduce deep compressive surface residual stresses that improve the durability of parts. A non-destructive measurement of residual stresses, their anisotropy, and distribution as a function of depth is being sought to verify initial process quality and residual stress retention over time. Laser-ultrasonic measurements of Rayleigh wave and surface skimming longitudinal wave (SSLW) velocities were used together to evaluate the magnitudes and directions of the two principal stresses independently of LPB-induced texture variations. The results agree with x-ray measurements at the surface. In addition, it was found that the laser-ultrasonic pulse generation mechanism was surface-process dependent.Peer reviewed: YesNRC publication: Ye