The influence of specimen geometry and notch on the hydrogen embrittlement of an SA372 steel for pressure vessels was investigated in this study. A slow strain-rate tensile (SSRT) test after the electrochemical hydrogen charging method was conducted on four types of tensile specimens with different directions, shapes (plate, round), and notches. The plate-type specimen showed a significant decrease in hydrogen embrittlement resistance owing to its large surface-to-volume ratio, compared to the round-type specimen. It is well established that most of the hydrogen distributes over the specimen surface when it is electrochemically charged. For the round-type specimens, the notched specimen showed increased hydrogen susceptibility compared with the unnotched one. A notch causes stress concentration and thus generates lots of dislocations in the locally deformed regions during the SSRT test. The solute hydrogen weakens the interactions between these dislocations by promoting the shielding effect of stress fields, which is called hydrogen-enhanced localized plasticity mechanisms. These results provide crucial insights into the relationship between specimen geometry and hydrogen embrittlement resistance.

1. 서 론
2. 실험방법
3. 실험 결과 및 고찰
    3.1. 미세조직 및 탄화물 분석
    3.2. 시편 형태와 노치 유무에 따른 수소취화 거동변화
4. 결 론
Acknowledgement

• 신희창(서울과학기술대학교 신소재공학과) | Hee-Chang Shin (Department of Materials Science and Engineering, Seoul National University of Science and Technology, Seoul 01811, Republic of Korea)
• 김상규(서울과학기술대학교 신소재공학과) | Sang-Gyu Kim (Department of Materials Science and Engineering, Seoul National University of Science and Technology, Seoul 01811, Republic of Korea)
• 김재윤(서울과학기술대학교 신소재공학과, 세아베스틸 기술연구소) | Jae-Yun Kim (Department of Materials Science and Engineering, Seoul National University of Science and Technology, Seoul 01811, Republic of Korea, R&D Center, SeAH Besteel, Gunsan 54007, Republic of Korea)
• 황병철(서울과학기술대학교 신소재공학과) | Byoungchul Hwang (Department of Materials Science and Engineering, Seoul National University of Science and Technology, Seoul 01811, Republic of Korea) Corresponding author