Effect of secondary orientation on room temperature tensile behaviors of Ni-base single crystal superalloys

The influence of secondary orientation and holes on the localization and the evolution of plasticity during room temperature tensile tests of thin wall specimens of a Ni-base single crystal superalloy were investigated. An ARAMIS system based on the digital image correlation technique was employed to in situ observe the strain distribution on the sample surfaces, and an in-situ scanning electron microscopy was used to in-situ observe the slip traces development during tensile tests. For the smooth specimens, the tensile strength of < 110 > specimen is slightly higher than that of < 100 > specimen ( < 110 > and < 100 > are the secondary orientations of the specimens). However, in the case of specimens with a hole in gauge section, detailed analysis indicates that 3-D tensile stress in the vicinity of the hole results in more slip systems initiated in < 100 > specimens, which may lead to stronger strain hardening. As a result, higher strength is obtained in < 100 > specimens with a hole. (C) 2016 Elsevier B.V. All rights reserved.