Shot peening of brittle materials - status and outlook

Shot peening is a common procedure to improve the static and cyclic strength of metal components by a combination of work hardening and the introduction of compressive stresses into the surface region. Our investigations through the last years showed that high compressive stresses of more than 1 GPa can also be introduced in brittle ceramics under specific shot peening conditions. These stresses significantly increase the near-surface strength. Based on the findings for ceramics, shot peening procedures have now been developed for cemented carbides and hard chromium platings. Recent investigations showed that, due to the higher fracture toughness of cemented carbides, shot peening could be performed using higher peening intensities leading to a higher gain in strength properties. Although chromium platings are less brittle than ceramics, shot peening of these layers are very challenging due to the formation of a micro-crack network being typically for these coatings. Nevertheless, first results indicate the possibility of a successfully shot peening of these coatings.