Abstract
Abstract Laser shock peening (LSP) is a reliable, repeatable, and successful surface technique for introducing high magnitude, deep compressive residual stresses that can significantly increase the fatigue life of metallic components. However, depending upon how the LSP treatment is applied, the induced residual stresses can result in the undesirable deformation of the part. In this work, traditional shot peening has been applied over LSP as a means to optimize the stress distribution at the surface of a part while constraining deformation. A single edge notch test specimen of AA7075 was laser peened local to the notch region and then shot peened over the entire central region. The resulting residual stress distribution has been characterized using neutron diffraction to measure the stress distribution in the bulk, and it was compared with (1) incremental center hole drilling to measure the stress distribution up to depths of ∼1 mm and (2) near-surface stresses obtained in a previous X-ray diffraction (XRD) study on nominally identical specimens subjected to the same surface treatments. For regions where the two techniques overlap, the residual stresses are in good agreement (within uncertainty). Comparing the bulk stresses obtained from neutron diffraction in this study and XRD data published elsewhere, it can be shown that shot peening applied after LSP has a profound effect on near-surface stresses; however, these effects disappear at depths of ∼0.7 mm or more.
Published Version
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