Compression deformation behavior of Zr–1Sn–0.3Nb alloy with different initial orientations at 650 °C

Zr is a hexagonal close packed metal which shows great anisotropy during deformation. To reveal the effect of initial orientations on deformation behaviors of Zr alloys at elevated temperatures, compression tests at 650 °C were performed for cylinder specimens which were cut from a Zr–1Sn–0.3Nb alloy sheet and make their compression axes (CA) tilt 0°, 30°, 60° or 90° to the normal direction (ND) of the sheet. Stress–strain curves of the specimens were obtained from the employed thermo-mechanical compression machine and microstructures of the deformed specimens were characterized by electron backscattered diffraction (EBSD) technique. Results show that yield strengths of the specimens drop with increasing the initial orientation. The strength drop is mainly attributed to a gradual increase of the Schmid factor (SF) for prismatic slip. A few image and image twins are also detected in the yielded specimens. With increasing the initial orientation, the dominant twinning mode changes from image to image. As the compression strain accumulates, dynamic recrystallization is found to occur in all specimens, testified by presence of fine recrystallized grains and/or decrease of the stress–strain curves. In addition, a strong effect of the initial orientation on suppressing the dynamic recrystallization is revealed and the reason is tentatively discussed.