| Title |
Evaluation of Hydrogen Embrittlement Sensitivity with Respect to Crystallographic Orientation of Single Crystal Ni Base Alloys |
| Authors |
윤희수(Hee Soo Yun); 다오반헝(Van Hung Dao); 권휴상(Hyusang Kwon); 이지훈(Jihun Lee); 남승훈(Seung Hoon Nahm) |
| DOI |
https://doi.org/10.3365/KJMM.2025.63.5.389 |
| ISSN |
1738-8228(ISSN), 2288-8241(eISSN) |
| Keywords |
Hydrogen embrittlement; Single crystal; Ni-based superalloy; Tensile test; Deformation behavior; Gas turbine |
| Abstract |
As demand for hydrogen, a clean energy source, has increased, hydrogen embrittlement caused by hydrogen penetration into materials has became a major challenge. This study evaluated the effect of crystallographic orientation on hydrogen embrittlement sensitivity, using single-crystal Ni-based superalloys that are used in hydrogen gas turbines. The two crystallographic orientations selected for testing were near the <110> and <111> directions. Specimens were first exposed to a 250℃, 10 MPa hydrogen environment for 4 days to allow hydrogen precharging. The hydrogen content within the specimen was measured via thermal desorption spectroscopy. To evaluate hydrogen embrittlement sensitivity, mechanical deformation was conducted by tensile loading. The hydrogen content in the <111> specimen was found to be approximately 16% higher than in the <110> specimen, but the hydrogen embrittlement sensitivity was determined to be higher in the <110>, at 74.0%. Both crystallographic orientations exhibited brittle characteristics regardless of hydrogen penetration and fractures were observed along two common dislocation slip directions. Deformation behavior was evaluated by comparing the crystal orientation of the microstructure before deformation with the change in crystal orientation due to deformation by misorientation. The deformation behavior in the <110> direction was relatively characterized by localized deformation regions with high misorientation, while the <111> direction showed more widespread deformation with lower misorientation. Upon hydrogen penetration, misorientation increased regardless of crystallographic orientation, and it was determined that the <110> direction, with its localized misorientation deformation behavior, was more sensitive to hydrogen embrittlement due to local stress concentration.(14 March Received, 15 April Accepted) |