Deforming TC6 titanium alloys at ultrahigh strain rates during multiple laser shock peening

The deformation mechanism of TC6 titanium alloys at ultrahigh strain rates ( > 10(6) s(-1)) during multiple LSP was investigated. When nanosecond pulse and 1000 MW laser irradiated on the materials, the high pressure plasma shock wave was induced and ultrahigh strain rates response was caused in the material. The TEM observation of the surface layer indicates that a layer of nanocrystalline has been formed and is unevenly distributed after a single impact. Increasing impact times could provide longer time and more energy to dislocation movement which refines the grains into smaller size and makes the distribution uniform. The hardness of TC6 titanium alloy has been improved by a single laser shock peening, forming a severe plastic deformted layer with a depth of 200 mu m. Increasing impact times will improve the hardness and effective depth. The XRD test shows that the position of diffraction peak did not show any change, but the Bragg diffraction peak was broadened. Dislocation activity is a prevalent deformation mechanism of TC6 titanium alloy in the grain refinement study. (C) 2013 Elsevier B.V. All rights reserved.