Melting as an extreme deformation mechanism at high strain rates

Abstract

Deformation, especially plastic deformation involving shock and impact in crystalline metal and alloy systems, begins as nonlinear dislocation phenomena which in the extreme deformation regime involving high strains and high-strain-rates leads variously to shear phenomena involving twinning and microband formation, dynamic recrystallization either as localized shear instabilities in shear bands or large volume solid-state flow, and finally localized melting. These mechanisms can be viewed as deformation state changes within some pressure-temperature regimes. In this work, we present examples of deformation-induced melting, especially in association with dynamic recrystallization (DRX). These examples include partial melting in explosive weld-wave vortex structures in connection with DRX in several dissimilar metal and alloy (explosive welded) systems, as well as projectile-target interactions for W single crystal rods and W rods clad with Inconel 718 (53 Ni, 17 Fe, 20 Cr) penetrating RHA steel targets at impact velocities ranging from 1.2 to 1.4 km/s.