Abstract
The relation between the ductile-brittle transition behavior and the specimen direction was investigated with beryllium sheet. Most of the basal planes of beryllim sheets used in this experiment were parallel to the rolling direction. But in the transverse direction there was a concentration of the basal poles at 25 degrees from the normal to the sheet. Two kinds of tensile test pieces, i.e. longitudinal and transverse specimens, were cut from the sheet. The tensile ductility of the longitudinal specimens was compared with that of the transverse specimens in the temperature range of 100°∼400°C.
The results obtained are as follows:
(1) Beryllium sheets were inferior in tensile ductility in the transverse direction to those in the longitudinal direction in the temperature range of 100°∼400°C. Furthermore, it was found that the shape of transverse tensile test curve was quite different from that of the longitudinal test curve.
(2) The effects of precipitation treatment and grain refinement on the tensile ductility were examined. Aging at 700°C for 120 hrs increased the transverse ductility at 400°C, though it was not observed below 300°C. On the other hand, the grain refinement from 180 μ to 40 μ increased the ductility of the transverse specimens at 300° and 400°C. Besides, the anomalous shape of the transverse tensile test curve was remarkably changed by the grain refinement.
(3) In the temperature range of 100°∼300°C, the tensile ductility decreased with the increasing rate of loading, while the ductility at 400°C did not vary or increased with the loading rate.
