Experimental and numerical investigation of the microstructural influence on the deformation behavior of notched cp-titanium specimens

Abstract

Abstract Notches lead to a decrease in the strength of machine parts in comparison to unnotched structures. The strength reduction is caused by stress concentration at the notch base. In static or dynamic calculations this effect is considered by the notch stress concentration factor. In this paper, simulations with a titanium single-crystal were carried out to analyze the dependence of the notch-stress concentration factor on the orientation of the anisotropic single-crystal material. Furthermore, numerical simulations and experiments with notched commercially pure titanium specimens have been performed to compare the stress–strain relationships until the ultimate tensile stress. The strain rate and grain size have been varied to identify dependencies on the microstructural situation which may influence the strength during the tests. After the tests, interrupted at ultimate tensile stress, metallographic sections were taken to reveal possible changes in microstructure. In the present investigation it is shown that for the single-crystal the notch-stress concentration factor depends strongly on the crystal orientation. Evidence is found that the grain size affects the strength of a notched specimen negatively, when the grain size is of the same size as the notch radius.