The microstructural response of a peened near-α titanium alloy to thermal exposure

 Peening and associated compressive residual stresses have been universally accepted to improve mechanical behaviour. This paper identifies for the first time conditions for which peening can be deleterious. Peening enhances the surface oxygen enrichment of Ti-834 after thermal exposure. This is attributed to the generation of deformation twins during the peening process, which act as short-circuit diffusional pathways for oxygen. The influence of microtexture and chemistry on the propensity for twinning, and thus oxygen enrichment, is also discussed.