Evaluation of methods for estimating shear fatigue properties of steels and titanium alloys

This study evaluated the accuracy of different methods in estimating shear fatigue behavior of steels and titanium alloys from properties which are easier to obtain such as monotonic properties and hardness. In order to achieve this goal, test results of 23 types of carbon steel, Inconel 718, and three types of titanium alloys commonly used in industry were found in the literature. In addition, two types of steel and a Ti-6Al-4V titanium alloy were subjected to axial monotonic and fatigue tests as well as torsion fatigue tests the results of which were used along with the data from literature. A reasonable correlation between uniaxial and shear fatigue properties of ductile and brittle behaving materials were found using von Mises and maximum principal strain criteria, respectively. Moreover, it was observed that for steels and Inconel 718 obtaining shear fatigue properties from uniaxial fatigue properties, which were in turn calculated from Roessle-Fatemi hardness estimation method, resulted in reasonable estimations. The shear fatigue properties estimated from the Roessle-Fatemi hardness method were also used for the analysis of variable amplitude axial-torsion fatigue tests performed on three types of ductile steel which resulted in reasonable fatigue life estimations. Furthermore, in order to use the Roessle-Fatemi hardness method for estimating the shear fatigue behavior of titanium alloys, this method was modified based on the uniaxial fatigue properties of titanium alloys.