단결정 Ni기 초합금의 결정방위에 따른 수소 취화 민감도 평가 (Evaluation of Hydrogen Embrittlement Sensitivity with Respect to Crystallographic Orientation of Single Crystal Ni Base Alloys)

서지정보

· 발행기관 : 대한금속·재료학회
· 수록지 정보 : 대한금속·재료학회지 / 63권 / 5호 / 389 ~ 398페이지
· 저자명 : 윤희수, 다오반헝, 권휴상, 이지훈, 남승훈

초록

As demand for hydrogen, a clean energy source, has increased, hydrogen embrittlement caused byhydrogen penetration into materials has became a major challenge. This study evaluated the effect ofcrystallographic orientation on hydrogen embrittlement sensitivity, using single-crystal Ni-based superalloysthat are used in hydrogen gas turbines. The two crystallographic orientations selected for testing were nearthe <110> and <111> directions. Specimens were first exposed to a 250oC, 10 MPa hydrogen environment for4 days to allow hydrogen precharging. The hydrogen content within the specimen was measured via thermaldesorption spectroscopy. To evaluate hydrogen embrittlement sensitivity, mechanical deformation wasconducted by tensile loading. The hydrogen content in the <111> specimen was found to be approximately16% higher than in the <110> specimen, but the hydrogen embrittlement sensitivity was determined to behigher in the <110>, at 74.0%. Both crystallographic orientations exhibited brittle characteristics regardlessof hydrogen penetration and fractures were observed along two common dislocation slip directions.
Deformation behavior was evaluated by comparing the crystal orientation of the microstructure beforedeformation with the change in crystal orientation due to deformation by misorientation. The deformationbehavior in the <110> direction was relatively characterized by localized deformation regions with highmisorientation, while the <111> direction showed more widespread deformation with lower misorientation.
Upon hydrogen penetration, misorientation increased regardless of crystallographic orientation, and it wasdetermined that the <110> direction, with its localized misorientation deformation behavior, was moresensitive to hydrogen embrittlement due to local stress concentration.

영어초록

As demand for hydrogen, a clean energy source, has increased, hydrogen embrittlement caused byhydrogen penetration into materials has became a major challenge. This study evaluated the effect ofcrystallographic orientation on hydrogen embrittlement sensitivity, using single-crystal Ni-based superalloysthat are used in hydrogen gas turbines. The two crystallographic orientations selected for testing were nearthe <110> and <111> directions. Specimens were first exposed to a 250oC, 10 MPa hydrogen environment for4 days to allow hydrogen precharging. The hydrogen content within the specimen was measured via thermaldesorption spectroscopy. To evaluate hydrogen embrittlement sensitivity, mechanical deformation wasconducted by tensile loading. The hydrogen content in the <111> specimen was found to be approximately16% higher than in the <110> specimen, but the hydrogen embrittlement sensitivity was determined to behigher in the <110>, at 74.0%. Both crystallographic orientations exhibited brittle characteristics regardlessof hydrogen penetration and fractures were observed along two common dislocation slip directions.
Deformation behavior was evaluated by comparing the crystal orientation of the microstructure beforedeformation with the change in crystal orientation due to deformation by misorientation. The deformationbehavior in the <110> direction was relatively characterized by localized deformation regions with highmisorientation, while the <111> direction showed more widespread deformation with lower misorientation.
Upon hydrogen penetration, misorientation increased regardless of crystallographic orientation, and it wasdetermined that the <110> direction, with its localized misorientation deformation behavior, was moresensitive to hydrogen embrittlement due to local stress concentration.

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