Fatigue notch sensitivity as a function of the notch to grain size relationship

¹ Mateis, INSA de Lyon, 20, Avenue Albert Einstein, 69621 Villeurbanne Cedex, France
² Department of Mechanical Engineering, University of Seville, 41092 Seville, Spain

^a Corresponding author: pablo.lorenzino@insa-lyon.fr

Abstract

This work presents experimental results showing the mode I fatigue behaviour of holed components as a function of the hole to grain size relationship. A wide range of notch size to grain size ratios are used, including cases where the notch size is on the order of, or even smaller, than the grain size. Making through-holes in the order of the grain size is very difficult in practice. So the technique used in this paper is to manufacture materials with very large grain size, on the order of a millimetre or even centimetre, then usual machines and tools can be used for making the notches. After the specimens are obtained and tested, the notch sensitivity is evaluated and it is shown how the notch sensitivity index of any material must always be defined in terms of its microstructure. It was found that for the same specimen geometry and loading conditions and identical stress concentrators, the influence of the stress concentrator is directly dependent on the relationship between their dimension and the grain size.