In-situ observation of crack initiation and propagation in Ni-based superalloy with film cooling holes during tensile test

The main aim of this work is to explore and analyze the crack initiation and propagation in nickel-based superalloy with film cooling holes (FCHs) during the in-situ tensile test. The stress value and position of crack initiation were determined by experiments and finite element analysis (FEA). Internal cracking of the metallic carbides (MC) composed by refractory elements has a greater impact on crack initiation and propagation. Both crack initiation and early expansion are Mode-I. The secondary crack spread in the opening type; however, the main crack spread in the form of slip separation. The material microstructure in crack tip plastic zone has a decisive effect on the crack propagation path. Finally, samples break along the {111} slip plane and perpendicular to the stress axis direction in the form of cross-cleavage. •Crack extends from the middle hole to the two sides holes.•Cracks exhibit I-type crack initiation characteristics.•Main crack propagation model exhibits slip separation.•Brittle carbides internal cracking and polymerization induce cracks path.•Samples break along the {111} slip plane in the form of cross-cleavage.