Abstract
In support of efforts to develop multiscale models of a variety of materials, we have performed a set of eleven gas gun impact experiments on 2169 steel, a high-strength austenitic stainless steel. These experiments provided carefully controlled shock, reshock, and release velocimetry data, with initial shock stresses ranging from 10 to 50 GPa. Both windowed and free-surface measurements on samples ranging in thickness from 1 to 5 mm were made to increase the utility of the data set. Target physical phenomena included the elastic/plastic transition (Hugoniot elastic limit), the Hugoniot, any phase transition phenomena, and the release/reshock paths (windowed and free-surface), with associated strength information. The Hugoniot is nearly linear in US–up space. Reshock tests with explosively welded impactors produced clean results, by contrast with earlier reshock tests with glued impactors which showed gap signatures. The free-surface samples, which were steps on a single piece of steel, showed lower wavespeeds for thin (1 mm) samples than for thicker (2 or 4 mm) samples. A preliminary strength analysis suggests the flow strength increases with stress from ∼1 GPa to ∼2.5 GPa over this range, consistent with other recent work but about 25% above the Steinberg model.
Highlights
AND BACKGROUNDWe have performed a set of gas gun impact experiments to measure strength properties of 2169 steel (21% Cr, 6% Ni, 9% Mn, balance Fe), partially in support of Lawrence Livermore National Laboratory (LLNL) efforts to develop multiscale models of a variety of materials.1,2 This set of experiments was designed to supply carefully controlled shock, reshock, and release velocimetry data for this steel, with initial shock stresses ranging from 10 to 50 GPa
The third experiment (SS-14) allowed comparison of compression/release waveforms measured with sapphire and lithium fluoride (LiF) windows at a stress level of 10 GPa
Free surface samples were included in this series of experiments to provide model developers benchmark data free from modeling uncertainties of window materials
Summary
We have performed a set of gas gun impact experiments to measure strength properties of 2169 steel (21% Cr, 6% Ni, 9% Mn, balance Fe), partially in support of Lawrence Livermore National Laboratory (LLNL) efforts to develop multiscale models of a variety of materials. This set of experiments was designed to supply carefully controlled shock, reshock, and release velocimetry data for this steel, with initial shock stresses ranging from 10 to 50 GPa. Ideally these pins would provide a time base for measuring wave propagation time, in practice these have not been accurate enough for present needs (65–10 ns), so we have assumed that the toe of the elastic wave propagates at the ultrasonically-measured longitudinal sound speed of 5.75 km/s. The third experiment (SS-14) allowed comparison of compression/release waveforms measured with sapphire and LiF windows at a stress level of 10 GPa
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