Effects on structure and mechanical properties of TC11 titanium alloy by laser shock peening

TC11 titanium alloy was treated by laser shock peening (LSP), while microstructure, residual stress and microhardness without/with LSP in different laser impacts were examined and compared via transmission electron microscope (TEM), X-ray diffractometer and microhardness tester. The high-cycle vibration fatigue test of TC11 titanium alloy standard vibration specimens was conducted to verify effects of LSP on the high-cycle fatigue property. The results indicated that severe plastic deformation was formed and grains on the surface were refined with high-density dislocations, dislocation cells. Nanocrystals were generated successively with increasing laser impact. The maximum residual stress reached -632.5 MPa in 10 impacts with 1500 μm thick plastic deformation layer. The microhardness was increased by 19% with 700 μm thick affected layer. The affected depth increased with the laser impact, but amplitude was limited. Fatigue limit of TC11 titanium alloy standard vibration specimens treated by LSP in 3 impacts had been improved from 483 MPa to 593 MPa.