Investigation Including a Testing Program to Study and Develop Methods for Improving Ductility of Beryllium.

摘要

A new technique for deforming ingot beryllium into sheet form was found. This technique was used to roll beryllium up to 96% at 300C and roll and upset between 80% to 90% at 200C without intermediate annealing. The recovery and recrystallization characteristics of the beryllium sheet were determined. It was found that the ingot beryllium rolled 96% began recovery below 400C while similar beryllium sheet deformed to 85% began recovery in the 500C region. Both temperatures are well below typical commercial fabrication temperatures and these low temperatures reflected the large amount of stored energy in the beryllium sheet. This resulted in a finer microstructure which in turn resulted in significantly higher mechanical properties,particularly bend ductility. The new fabrication technique was used to make polycrystalline high purity (6zone pass and 12zone pass) beryllium sheet. Evidence was found that twinning contributed to the sheet making deformation process in the high purity beryllium sheet. The recovery and recrystallization behavior of this sheet was determined and it appears quite feasible to make fine grain high purity ingot beryllium sheet. (Author)