Stress-Strain Behavior of Nb Single Crystal Tensile Specimens with Different Grain Orientations

Nine Nb single crystal tensile specimens with different grain orientations were extracted from a Ningxia ingot slice. All specimens were deformed to 40% engineering strain, and the stress-strain curves are presented. OIM scans were done at the center of the gauge length of each specimen before and after deformation to investigate the effect of strain on grain orientations. As a reference, OIM scans were also done on undeformed specimens that were cut adjacent to the deformed specimens. Some of the undeformed specimens show a noticeable orientation gradient along the gauge length. The effect of this gradient on the deformation behavior is examined. SEM images on the top and transverse surfaces of the deformed specimens were taken in order to identify slip systems. The results are compared with crystal plasticity finite element simulations of the same experiments to examine how well models can predict observed slip activity.