Microstructure and tensile behaviour of pure titanium produced after high-energy shot peening

In this study, the microstructure and tensile behaviour of pure titanium processed by means of high-energy shot peening have been studied. The results show that a nanocrystalline surface layer is prepared on the surface of pure titanium. During severe deformation, the dislocations, twins and slip bands with single orientation are formed first, then the intersections of twins and slip bands are observed, and then the subgrains appear near or in the slip bands and finally the randomly oriented nano-grains are formed due to the further breakdown. After high-energy shot peening, the ultimate tensile strength and the yield strength increase by 27 and 40%, while the elongation decreases by 64% after treatment, due to the increasing dislocation density, micro-strain and the grain refinement.