PSI - Issue 42

Hiroshi Nishiguchi et al. / Procedia Structural Integrity 42 (2022) 1442–1448 Author name / Structural Integrity Procedia 00 (2019) 000 – 000

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but small cracks along the {110} planes were also initiated from the four corners of the indent. A laser Raman microscope was used to measure the residual stress distribution before and after the hydrogen gas exposure, with four hydrogen gas pressures (from 10 to 100 MPa) applied at 270 o C for 24 h. These investigations led to the following conclusions: 1. Crack growth clearly occurred after hydrogen gas exposure. Up to a hydrogen gas pressure of 35 MPa, the crack growth ratio increased with increasing gas pressure. However, for the hydrogen pressures above 35 MPa, the crack growth ratio was saturated, and the upper limit of the crack growth ratio was approximately 9%. 2. It was found that compressive residual stress around the indentation was decreased by hydrogen gas exposure. The effect of the temperature (270 o C) on the residual stress is regarded to be negligible. 3. Based on the experimental results, the compressive residual stress field around a crack tip, such as in fatigue cracks, may be reduced by the introduced hydrogen, and crack propagation should be promoted in a hydrogen gas environment due to the reduction of the crack closure effect, resulting in lower fracture toughness. Acknowledgments This work was partially supported by the Ministry of Education, Science Sports and Culture, Grant-in-Aid for Scientific Research (A), 2018-2022 (18H03848, Kenji Higashida) and Grant-in-Aid for Scientific Research (C), 2021-2023 (21K03763, Hiroshi Nishiguchi). References Beachem, C. D., 1972, A New Model for Hydrogen -Assisted Cracking (Hydrogen “ Embrittlement ” ). Metallurgical Transactions 3, 437 – 451. Birnbaum, H.K., Sofronis, P., 1994. Hydrogen-Enhanced Localized Plasticity – A Mechanism for Hydrogen-Related Fracture. Materials science and engineering Series A 176, 191 – 202. Ferreira, P. J., Robertson, I. M., Birnbaum, H. K., 1998, Hydrogen Effects on the Interaction between Dislocations. Engineering Fracture Mechanics, Acta Materialia, 46, 1749-1757. Higashida, K., Narita N., 1990. Crack Tip Plasticity and Its Role in the Brittle-to-Ductile Transition. Japanese Journal of Applied Physics Ser.2, 39 – 43. Higashida, K., Narita N., Tanaka, M., Morikawa, T., Miura, Y., Onodera, R., 2002. Crack tip dislocations in silicon characterized by high-voltage electron microscopy. Philosophical Magazine A82, 3263 – 3273. Higashida, K., Tanaka, M., Matsunaga, E., Hayashi, H., 2004. Crack Tip Stress Fields Revealed by Infrared Photoelasticity in Silicon Crystals. Materials Science and Engineering A, 387-389, 377 – 380. Higashida, K., Tanaka, M., Hartmaier, A., Y. Hoshino, 2008. Analyzing crack-tip dislocations and their shielding effect on fracture toughness, Materials Science and Engineering A, 483-484, pp. 13 – 18. Matsuoka, S., Tanaka, H., Homma, N., Murakami, Y., 2011. Influence of hydrogen and frequency on fatigue crack growth behavior of Cr – Mo steel. International Journal of Fracture 168, 101 – 112. Matsuoka, S., Matsunaga, H., Yamabe, J., Hamada, S., Iijima, T., 2017. Various Strength Properties of SCM435 and SNCM439 Low-Alloy Steels in 115 MPa Hydrogen Gas and Proposal of Design Guideline. Transactions of the JSME 83, 17-00264 – 17 – 00264. Murakami Y., Matsuoka S., Kondo Y., Nishimura S., 2012. Mechanism of Hydrogen Embrittlement and Guide for Fatigue Design. Yokendo Ltd., Tokyo, Japan. Nagumo, M., 2001. Function of Hydrogen in Embrittlement of High-Strength Steels. The Iron and Steel Institute of Japan 41(6), 590 – 598. Narita, N., Higashida, K., Torii, T., Miyaki, S., 1989. Crack-tip Shielding by Dislocations and Fracture Toughness in NaCl Crystals. Materials Transaction JIM 30, 895 – 907. Narita, N., Shiga, T., Higashida, K., 1994. Crack-impurity interactions and their role in the embrittlement of Fe alloy crystals charged with light elements. Materials Science and Engineering. A176, 203 – 209. Ogawa, Y., Matsunaga, H., Yamabe, J., Yoshikawa, M., Matsuoka, S., 2018. Fatigue limit of carbon and Cr – Mo steels as a small fatigue crack threshold in high-pressure hydrogen gas. International Journal of Hydrogen Energy 43, 20133 – 20142. Oriani, R. A., Josephic, P. H., 1974. Equilibrium Aspects of Hydrogen-Induced Cracking of Steels. Acta Metallurgica 22, 1065 – 1074. Seager, C. H., Anderson, R. A., 1988. Real ‐ time observations of hydrogen drift and diffusion in silicon. Applied Physics Letters 53, 1181. Yamabe, J., Itoga, H., Awane, T., Matsuo, T., Matsunaga, H., Matsuoka. S., 2016. Pressure Cycle Testing of Cr-Mo Steel Pressure Vessels Subjected to Gaseous Hydrogen. 138, 1 – 13