Laser shock peening for enhanced fatigue resistance in steel structures: Insights from Q960 steel study

Fatigue damage of steel structures is often likened to the "cancer" of structural engineering. Fatigue failure, characterized by the absence of apparent signs before occurrence, usually leads to significant losses. To investigate the potential of laser shock peening (LSP) as an effective method for improving the fatigue performance of steel structures, square plates and compact tension (CT) specimens made of Q960 structural steel were designed. The surface integrity, fatigue crack growth (FCG) performance, microstructural grain size, and fracture morphology of specimens were compared at different laser shock parameters. The results show that LSP implanted a high level of beneficial residual compressive stress in a mild way, and no obvious surface defects were introduced. A noticeable retardation effect was found in the FCG of LSPed specimens, and this effect becomes more pronounced with the increase of laser pulse energy. Compressive residual stress is a more dominant factor in enhancing fatigue performance compared to grain refinement for the small-grained metals studied. LSP can effectively reduce the FCG rate of Q960 high-strength steel, showing promising application prospects in strengthening the fatigue hazard zone of steel structures.