Influence of the ratio between specimen thickness and grain size on the fatigue and tensile properties of plain and notched aluminium plate specimens

Abstract

The influence of the ratio between specimen thickness (t) and grain size (D) on the tensile and fatigue properties of plain and notched aluminium plate specimens has been studied. Grain sizes ranging from 66 μm to 9.74 mm have been prepared and used in the tests. The observed decrease on tensile properties when D is comparable, or even exceeds, t can be accounted for by adding an additional negative exponential term to the Hall–Petch equation. An exponential decrease has also been found in endurance limits as grain size approaches plate thickness in plain specimens. In notched specimens, however, increasing grain size has two opposing effects, namely: a decrease in the plain endurance limit associated with the decrease in thickness relative to grain size and an increase in notched fatigue strengths brought about by a decrease in notch sensitivity.