Influence of strain rate and temperature on the mechanical behavior of beryllium

The compressive stress-strain response of three grades of beryllium were studied as a function of strain rate and temperature. Grades S200D, E, and F represent a historical perspective of beryllium processing from the 1960's through 1990's technology. The purpose of this study was to measure the mechanical behavior of beryllium over a range of deformation conditions for constitutive model development and to obtain microstructural evidence for deformation mechanisms. The compressive stress-strain response was found to be independent of grade and strongly dependent on the applied strain rate between 0.001 and 8000 s(-1). The strain-hardening response displayed a moderate temperature dependence between 77 degrees K and 873 degrees K. Microstructural examination of SHPB specimens revealed that twinning was extensive at strains above 7%. A SHPB sample deformed to over 20% strain contained both twinning and grain boundary microcracking.