Fatigue behaviour of light alloys with ultrafine grain structure produced by severe plastic deformation: An overview

The fatigue behaviour of light alloys with grain sizes reduced to the micron or submicron scale by severe plastic deformation (SPD) is reviewed. While the enhancement of tensile strength by this extreme grain refinement can be quite appreciable, the fatigue strength is usually not improved to the same extent. This observation is common to Al, Mg and Ti based alloys and does not appear to be attributable to a particular crystallographic structure. Various effects that may influence this behaviour are reviewed, and emphasis is put on the role of the alloying effects as the main contributors to fatigue strength. The direct contribution of solutes to fatigue strength is usually stronger than their indirect effect through the influence of solutes on the grain refinement. Recent examples from literature and our own work are presented to corroborate the views expressed in the article.