Ultrasonic Vibration Assisted Laser Processing: A Hybrid Paradigm for Extreme Surface Enhancement

Traditional laser processing techniques offer many advantages, but they often encounter limitations such as heat-affected zones, recast layers, residual tensile stresses, and poor surface finish. The integration of ultrasonic vibration (UV) presents a promising hybrid approach to overcome these challenges by introducing beneficial effects like acoustic softening, cavitation, and enhanced mass transfer. This paper provides a comprehensive review of the recent advancements in ultrasonic vibration-assisted laser processing for surface enhancement. It meticulously examines three critical techniques: ultrasonic vibration assisted laser polishing (UVA-LP), ultrasonic vibration assisted laser shock peening (UVA-LSP), and ultrasonic vibration assisted laser drilling (UVA-LD). For each technique, the review systematically explores the design of ultrasonic systems, the underlying multi-physics mechanisms of property enhancement, and the resultant improvements in surface integrity, mechanical performance, and processing efficiency. A dedicated comparative synthesis identifies common mechanisms such as acoustic streaming, cavitation, and stress-wave coupling that govern all three processes and provides a unified process–structure–property correlation map. The analysis reveals that UVA-LP effectively reduces surface roughness and refines microstructures by modulating molten pool dynamics. UVA-LSP synergistically combines high-strain-rate deformation with ultrasonic impacts to generate profound compressive residual stresses and superior grain refinement, significantly enhancing fatigue life and wear resistance. Meanwhile, UVA-LD drastically improves drilling efficiency, reduces taper angle, minimizes recast layers, and enhances hole quality through improved melt expulsion. This review synthesizes findings from a wide body of literature to demonstrate that the strategic application of ultrasonic vibration significantly amplifies the benefits of laser processing, leading to superior mechanical properties, tribological performance, and overall component longevity. The paper concludes by affirming the transformative potential of UVA laser techniques and suggesting directions for future research, including intelligent process control, in situ monitoring, digital twins, multi-field assistance, and integration with additive manufacturing.