Crack Growth Process of Ni-Single Crystal with Cathodic Hydrogen Charging

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Notched tensile tests {orientation: tensile axis [001], direction of notching [010]or[110] } were performed to investigate the crack growth process in Ni-single crystal with hydrogen cathodic charging. Y-shaped hillocks and striation-like patterns were observed on the fracture surfaces of hydrogen embrittled specimens using the scanning electron microscope (SEM). The Y-shaped hillocks are exactly matched on both fracture surfaces of a specimen. In addition, cleavage fracture is occurred between a Y-shaped hillock and next one. It means that the cleavage fracture is occurred at first, and the Y-shaped hillock is secondary formed. It is considered that the striation-like pattern is formed by the localized slips and cleavage fracture between them. Peach-Koehler’s law leads that the dislocations on the equivalent slip systems with (111 ) [101] are subjected to the highest force of all dislocations at the crack tip. Furthermore, Ni-hydride was not observed on the surface of specimen just after charging hydrogen. Thus, it was concluded that Y-shaped hillock and striation-like pattern were occurred in Ni-single crystal with charging hydrogen under condition that Ni-hydride is not formed.

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Periodical:

Key Engineering Materials (Volumes 348-349)

Edited by:

J. Alfaiate, M.H. Aliabadi, M. Guagliano and L. Susmel

Pages:

137-140

Citation:

H. Matsui and N. Takano, "Crack Growth Process of Ni-Single Crystal with Cathodic Hydrogen Charging", Key Engineering Materials, Vols. 348-349, pp. 137-140, 2007

Online since:

September 2007

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$38.00

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