Experimental investigation of laser peening on Ti17 titanium alloy for rotor blade applications

•Laser peening on Ti17 titanium alloys is investigated.•Roughness and residual stress value were grown on laser energy and impact times.•Hardened layer depth increases significantly with laser peening impact times.•Laser peening is effectively in lower fatigue stress level.•Laser peening makes the microstructures evolution. Laser peening is an innovative surface treatment technique, and can significantly improve the mechanical performance of metallic components. To investigate the fatigue life of Ti17 titanium alloy by laser peening, laser peening experiment was undertaken using Nd:YAG laser system with the pulse-width of 15ns and max pulse-energy of 7J. Firstly, the mechanical properties and microstructure with different laser peening parameters were investigated, which were measured and observed by Vickers indenter, X-ray diffraction, scanning electron microscope and transmission electron microscope. Micro-hardness and compressive residual stress distribution was remarkably improved. High-density dislocations and fine-grains were observed in the surface layer. Then, several stress levels were chosen to be applied on the tension and compression fatigue specimens. The fatigue life and fracture mechanism of the specimens without- and with-laser peened were compared, and the strengthening mechanism was indicated by analyzing the effects on the microstructure and residual stress evolution. The results demonstrate that laser peening could effectively improve the fatigue life of Ti17 titanium alloy.