We are executing a systematic study to quantify the effects of specific microstructural features on the spall behavior of 99.999% copper. Single crystals with [100] orientation, polycrystals with three grain sizes, and internally oxidized single crystals are shocked with Cu flyers at velocities from 300 to 2000 m/s using a 35‐mm single/two‐stage light gas gun. VISAR measurements of the free surface velocity are used to characterize the spall pullback signal and details of the ringing. The high purity single crystals exhibit the highest spall strength followed by the large, medium and small grain size polycrystalline samples. Cu − 0.15 wt.% Si single crystals have been internally oxidized to produce a fine dispersion of 350 nm silica particles. These samples exhibit the lowest spall strength, a factor of two and greater below the high purity single crystals.

Grain size and pressure effects on spall strength in copper

The results of an experimental investigation designed to determine the effect of damage created by hydrostatic tensile loading on the properties of copper are reported. Three metallurgical conditions of half‐hard OFHC copper were investigated; as worked; annealed 2hr at 400°C (∼40 micron grain diameter); and annealed 2hr at 800°C (∼80 micron grain diameter). Mechanical property characterization included uniaxial compression tests. High rate plasticity and damage was introduced by Taylor and rod‐on‐rod impact tests. The damage from the high rate experiments was characterized using optical and scanning electron microscopy. Quasi‐static compression specimens machined from recovered high rate samples were tested to determine the influence of damage on the mechanical response of the material. The compression test results will be discussed in relationship to the starting microstructure and the extent of damaged introduced into the material.

R. J. De Angelis

Papers

Damage Characterization in Copper Deformed under Hydrostatic Stress — Experimental Analysis