優先方位をもつ多結晶亜鉛の引張挙動

抄録

The present work aims at the discussion about the influence of deformation twinning and basal- and pyramidal-slips on the stress-strain characteristics of zinc polycrystal specimens. For this purpose, the tensile tests have been made under 2000kg/cm² hydrostatic pressure on two groups of specimens of cold-rolled zinc sheets; one group has the tensile axis coinciding with the rolling direction and the other perpendicular to that direction.
The results are summarized as follows:
(1) Hydrostatic pressure has no influence on the stress-strain behaviors of the specimens tested. Every specimen is ductile even under ordinary pressure, as expected from the grain size and texture of the specimen material.
(2) The growth of deformation twinning raises the flow stress of a polycrystalline specimen. This is mainly due to the effect that each of the twins subdivides each grain.
(3) Plastic flow in a zinc polycrystal is caused by both basal- and pyramidal slips.
(4) The strain hardening behavior of a zinc polycrystal depends largely on pyramidal slips.
(5) The flow stress is about 20% higher in the extension along the transverse direction than that along the rolling direction.
(6) It seems that the low strain hardening rate of a zinc polycrystal results mainly from the dynamic recovery of dislocations in pyramidal slips. In addition to this, the stress relief due to the nucleation and growth of the twins should play an important role when a specimen has some extent of the preferred orientation of crystals.