Improvement of structure and mechanical properties of TC6 titanium alloy with laser shock peening

In order to implement the laser shock peening (LSP) technology on the TC6 titanium alloy aero-engine blade, TC6 titanium alloy was treated by LSP. Microstructural characteristics, microhardness and residual stress on the cross-section of TC6 titanium alloy after LSP were tested with X-ray diffraction (XRD), transmission electron microscope (TEM), microhardness tester and residual stress tester, and vibration fatigue limit was obtained by high-cycle fatigue test. The results demonstrated that the original structure was refined, and high density dislocation, dislocation cell, subgrain and nanocrystallite generated with laser impact increasing. Besides, on the aspect of mechanics performance, the surface microhardness was increased by 19% with a 700-μm-depth affected layer under one laser impact. The greatest residual stress value was -608.5 MPa on the surface in ten impacts and at 500 μm depth the value was still above -100 MPa. With three impacts, the fatigue limit of standard fatigue specimens was improved by about 20%.