Effect of Small Preliminary Deformation on the Evolution of Elastoplastic Waves of Shock Compression in Annealed VT1-0 T
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ISORDER, AND PHASE TRANSITION IN CONDENSED SYSTEM
Effect of Small Preliminary Deformation on the Evolution of Elastoplastic Waves of Shock Compression in Annealed VT1-0 Titanium G. I. Kanel’a,c, G. V. Garkushinb,c,*, A. S. Savinykhb,c, and S. V. Razorenovb,c a Joint
b
Institute for High Temperatures, Russian Academy of Sciences, Moscow, 125412 Russia Institute of Problems of Chemical Physics, Russian Academy of Sciences, Chernogolovka, Moscow oblast, 142432 Russia c National Research Tomsk State University, Tomsk, 634050 Russia *e-mail: [email protected] Received April 4, 2018
Abstract—The evolution of an elastoplastic waves of shock compression in VT1-0 titanium in the as-annealed state and after preliminary compression is measured. A preliminary strain of 0.6% and the related increase in the dislocation density are found to change the deformation kinetics radically and to decrease the Hugoniot elastic limit. An increase in the preliminary strain from 0.6% to 5.2% only weakly changes the Hugoniot elastic limit and the compression rate in the plastic shock wave. The measurement results are used to plot the strain rate versus the stress at the initial stage of high-rate deformation, and the experimental results are interpreted in terms of dislocation dynamics. DOI: 10.1134/S1063776118080022
1. INTRODUCTION The study of the temperature–rate dependences of the deformation and fracture resistance of metals and alloys in the submicrosecond mechanical loading range makes it possible to investigate the main laws of deformation-induced defect motion and to create a basis for developing wide-range models and constitutive relationships to calculate high-rate deformation and fracture under various, including technological, conditions. Studies in this field are performed using the methods of the physics and mechanics of shock waves in condensed matter and are based on measuring and analyzing the structure of elastoplastic waves of shock compression and their evolution during the propagation in materials [1–6]. In particular, in recent years we carried out an extensive series of experiments to study the temperature–rate dependences of the deformation resistance of metals and alloys with various crystal structures and found that the behavior of solids at high strain rates can differ qualitatively from that under normal conditions [4, 7]. In particular, we revealed an anomalous increase in the plastic flow stress with temperature at a high strain rate. We determined the set of materials in which this phenomenon can occur depending on the relation between the contributions of phonon viscosity and “barrier” forces, including the forces created by Peierls–Nabarro barriers and hardening inclusions.
In investigations, we arrived at the conclusion that the detected high initial strain rates can be explained on the assumption about intense dislocation multiplication at the very early stages of deformation in an elastic precursor. To check this assumption, we decided to measure the evolution of an elastoplastic wave of shock compr
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