Relationship between the fatigue limit and the mechanical strength of metals

An investigation of the relationship between the fatigue limit of surface-strengthened metals and their tensile and bending properties has revealed that the internal fatigue limit (the critical stress to initiate and propagate a fatigue micro-crack in the interior of a specimen — an intrinsic property parameter of the metal) can be illustrated by the resistance to mini-plastic deformation, which is close to the static bending and tensile stresses at the strain value of 0.1%. Therefore, the internal fatigue limit of metals can be determined easily and used to predict the fatigue limit of surface-strengthened metals. An explanation for the results is that the primary processes of yielding and fatigue-crack initiation are approximately the same.