Laser shock peening (LSP) is an advanced surface-strengthening technology that improves the anti-fatigue performance of metallic components. However, there is a significant barrier to the application of thin-walled components because the high-energy laser causes deformation and nonuniformity of compressive residual stress, thereby reducing fatigue performance. In this study, an LSP technology based on a low-pulse-energy laser was developed. We applied it to a thin-walled AA7075 aluminium alloy specimen (∼4 mm thickness) and achieved an improvement in the high-cycle fatigue limit of 20.4 and 37.0% for the smooth and pre-cracked fatigue specimens, respectively, in the absence of deformation. It was discovered that the enhanced dynamic nanoscale precipitation and dislocation multiplication effects of the high-pressure shock wave contribute to microstructure stability under cyclic loading, resulting in high compressive residual stress stability. Moreover, the unique heterogeneous grain structure on the surface layer subjected to LSP at low pulse energy effectively restrains crack initiation and propagation. Because these findings apply to a wide range of alloys, the current results create new avenues for improving the fatigue performance of thin-walled components.

激光冲击强化 (LSP) 是一种先进的表面强化技术，可提高金属部件的抗疲劳性能。然而，由于高能激光会导致变形和压缩残余应力不均匀，从而降低疲劳性能，因此薄壁部件的应用存在很大障碍。在这项研究中，开发了一种基于低脉冲能量激光的 LSP 技术。我们将其应用于薄壁 AA7075 铝合金试样（~4 mm 厚），在没有形变。研究发现，高压冲击波增强的动态纳米级析出和位错增殖效应有助于循环载荷下的微观结构稳定性，从而产生高压缩残余应力稳定性。此外，在低脉冲能量下经受 LSP 的表面层上独特的异质晶粒结构有效地抑制了裂纹的萌生和扩展。由于这些发现适用于范围广泛的合金，目前的结果为改善薄壁部件的疲劳性能开辟了新途径。