High-speed Deformation and Failure of Titan Alloy

Abstract

The paper presents the results of a study of the dynamic properties of 3M titanium alloy under tension, carried out using the Kolsky method, as well as the results of determining the spall strength obtained using a VISAR laser interferometer. The experiments using the split Hopkinson pressure bar were carried out in the range of strain rates of 700 - 1500 s_1. In this experiments, dynamic strain diagrams were obtained, according to which the yield strength σ0.2 and the tensile strength were determined. The yield strength of the studied material increases with increasing strain rate from 700 MPa to 800 MPa. Since the 3M alloy does not experience hardening with increasing strain, fracture begins at stress close to yield strength. The tensile strength of this alloy under uniaxial tension (temporary tensile strength) also grows slightly from 700 MPa to 800 MPa with increasing strain rate. The ultimate plastic fracture characteristics of a titanium alloy (elongation and relative narrowing after rupture) are practically independent of the strain rate. In plane-wave experiments, spall strength was studied in the range of strain rates of 2 · 104 - 5 · 104s-1. The obtained values of spall strength lie in the range of 1.6 - 4 GPa, which significantly exceeds the values obtained under static loading and the values obtained in experiments using the Kolsky method, which is apparently associated with both the influence of the strain rate and the influence volumetric stress state in a plane-wave experiment.