Effect of the rolling parameters on the structure and mechanical properties of the beryllium sheets

In this work, a molding material of three grades was used: grade A (99.95 % of beryllium), grade B (99.87 % of beryllium), and grade C (99.2% of beryllium). The workpieces, casted in vacuum, initially were extruded at 850 °С and then swaged. The rolling temperature was 500, 700, and 900 °С. For all grades, the tensile strength aB in flex test increases with a decrease of the rolling temperature. With an increase in the total compression degree from 20 to 90% at the temperature of 900 °С, the size of subgrains in the beryllium sheets of grade B does not essentially change and remains about 10 ^m. After 30 minutes of the annealing at the temperature 700 °С the structure of the beryllium sheets of grade A becomes recrystallized with an average grain size of 29 ^m. After recrystallization, the tensile strength aB decreases by 15% and the values of the elongation and transverse contraction decrease by two times. The temperature of 850-900 °С and a single compression up to 30% are the optimum rolling conditions. Thus, the appropriate combination of structural behavior and paste-forming properties can be obtained in material with subgrained structure in conditions of a high deformation temperature and high material purity.

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