Mingjia Wu

Laser shock peening (LSP) is an advanced surface modification technique that significantly enhances the fatigue resistance of metallic components through the synergistic implantation of deep compressive residual stresses (CRSs) and gradient microstructural refinement. Existing investigations have shown that LSP can generate strengthening layers extending from several hundred micrometers to approximately 1 mm in depth, with affected zones reaching 5–6 times the depth typically achieved by conventional shot peening in representative titanium alloys. In specific cases, LSP has increased the fatigue limit from 483.2 MPa to 593.6 MPa, corresponding to an improvement of approximately 22.8%, while optimized treatment of Ti-17 compressor blades has extended fatigue life by more than two orders of magnitude. This review systematically elucidates the anti-fatigue strengthening mechanisms of LSP across a range of metallic systems, with emphasis on three key aspects: (i) the mechanistic retardation of fatigue crack initiation and propagation, mediated by CRS-induced reductions in the stress intensity factor and enhanced crack closure effects; (ii) the parametric sensitivity of surface integrity and stress field homogeneity to laser energy density, spot overlap ratio, and multiple-impact sequencing; and (iii) the process-specific characteristics of emerging LSP variants, including laser peening without coating, warm laser shock peening, and cryogenic laser shock peening. Furthermore, we critically evaluate the role of multiscale numerical simulations—encompassing macroscopic finite element analysis, mesoscopic crystal plasticity modeling, and molecular dynamics—in optimizing process parameters and predicting fatigue life. By integrating experimental, computational, and theoretical perspectives, this review establishes a coherent process–structure–property framework to guide the rational design of LSP protocols for targeted fatigue performance enhancement.

Electrically assisted processing of metallic materials has emerged as a promising paradigm for reducing deformation resistance while concurrently tailoring microstructure and service-related properties under coupled electrical, thermal, and mechanical fields. This review focuses on deformation-dominated and surface-strengthening scenarios, examining recent advances from three interconnected perspectives: fundamental mechanisms, microstructural evolution, and property responses. Available evidence suggests that Joule heating typically constitutes the dominant contribution under high-duty-cycle or near-steady-state current conditions, whereas non-thermal electroplastic effects become increasingly pronounced under short-pulse, high-current-density, and temporally decoupled loading regimes. Current assistance can accelerate recovery and recrystallization, refine grain structure, modify crystallographic texture, and alter phase transformation and precipitation kinetics. Additionally, it can relax or redistribute residual stresses while reducing flow stress and forming forces. In select hybrid surface treatments, these microstructural modifications translate into enhanced resistance to fatigue, wear, and corrosion. Nevertheless, the available evidence precludes a single universal explanation, given that current crowding, defect-selective heating, electron–dislocation interactions, and magnetic effects operate concurrently, with their relative importance varying across material systems and processing conditions. Moving forward, establishing a unified framework that links electrical parameters, defect evolution, microstructure, and performance is imperative, with focused efforts on the quantitative delineation of thermal and non-thermal contributions, predictive constitutive modeling, residual stress stability, and industrial scalability.