孔径对第三代镍基单晶高温合金DD33板式试样室温拉伸性能的影响

Plate tensile specimens were machined from a Ni- base single crystal (SC) superalloy DD33, holes with various diameters were electrochemically machined (ECM) in the middle of the specimens. The strain fields around the holes during room temperature tensile tests were in-situ observed by an ARAMIS - optical deformation analysis system based on the digital image correlation (DIC) technique and the fracture surface was observed by scanning electron microscope (SEM). It was demonstrated that the yield strength and ultimate tensile strength decreased with the increase of hole diameter from 0.5 mm to 0.9 mm. Strain concentrated in the vicinity of the hole. The maximum strain increased slightly during elastic deformation. However, once plastic deformation began, it increased rapidly above its elastic value. In addition, the maximum strain and strain gradients adjacent to the holes increased with the increase of the hole diameter from 0.5 mm to 0.9 mm. This work is critical for understanding the crack initiation around the cooling holes with different diameters in the SC blade.