Effect of skew angle of holes on the tensile behavior of a Ni-base single crystal superalloy

Holes of various skew angles were electrochemically machined (ECM) in the middle of the plate specimens in a Ni-base single crystal (SX) superalloy. The surface strain fields around the holes during tensile test at room temperature were in-situ observed by an ARAMIS - optical 3D deformation analysis system based on the digital image correlation (DIC) technique. It was demonstrated that both the yield stress and the tensile elongation increased with the increase of the skew angles from 30° to 90°. Strain concentrated at the acute side of the skew holes. The results were analyzed based on the crystallographic structure of specimens and the slip traces observed on fracture surfaces.