Effect of femtosecond laser shock peening on surface integrity and fatigue property of ultra-thin-walled Ti6Al4V

Complex thin-walled titanium alloy components, such as the metal-reinforced edges of fan blades, commonly have wall thicknesses ranging from 0.5 mm to 2.5 mm and are widely used in the aerospace industry. However, their relatively low stiffness and limited fatigue strength restrict their performance under high-amplitude fatigue loading. To address these challenges, this study introduces a femtosecond laser shock peening (FLSP) technique that utilizes ultrashort pulse durations to enhance the surface properties of ultra-thin-walled Ti6Al4V. The technique creates periodic nanostructures on the 1 mm thick Ti6Al4V surface, generating a residual stress layer approximately 100 μm deep and a hardened layer with a hardness increase of up to 27.1%. As a result, the FLSP treatment improves the high-cycle tensile fatigue limit of Ti6Al4V by approximately 12.2%. The femtosecond laser shock wave induces high-amplitude compressive residual stresses in the shallow surface layer, while micron-scale laser spots allow precise regulation of local stress fields, improving the uniformity of the global stress distribution. These results provide a theoretical foundation for strengthening complex thin-walled components and offer a basis for the development of more effective surface enhancement techniques for such materials.