Application of Electron Channelling Contrast Imaging (ECCI) to Investigate the Mechanism of Discontinuous Crack Propagation in Fe–Si Alloy
,
,
,
and
Article Sidebar
Full Text: 
PDF
Abstract
Electron Channeling Contrast Imaging (ECCI) was applied to elucidate the mechanism of discontinuous crack propagation in a single-crystalline Fe–3 wt%Si alloy subjected to tensile loading in air. Subsurface observations revealed symmetrically activated slip systems and regularly spaced slip bands emitted from the crack tip. Intersecting slip bands and dislocation cell structures were identified ahead of the crack tip, forming low-energy dislocation structures that locally hinder crack advance. The spacing of these dislocation features was found to coincide with the striation spacing observed on the fracture surface, indicating that crack growth increments are governed by intrinsic dislocation arrangements rather than global crack length. A microstructure-controlled mechanism involving cyclic dislocation emission, work hardening, crack advance, and arrest is proposed.
Tóm tắt
Kỹ thuật tương phản kênh điện tử (Electron Channeling Contrast Imaging – ECCI) được áp dụng nhằm làm sáng tỏ cơ chế lan truyền vết nứt gián đoạn trong hợp kim Fe–3 wt%Si đơn tinh thể chịu tải kéo trong môi trường không khí. Kết quả từ các quan sát dưới bề mặt cho thấy sự hoạt hóa đối xứng của các hệ trượt và sự hình thành các dải trượt có khoảng cách đều đặn phát ra từ đầu vết nứt. Các dải trượt giao cắt và cấu trúc lệch mạng được xác định phía trước đầu vết nứt, hình thành nên các cấu trúc lệch mạng có vai trò cản trở cục bộ sự tiến triển của vết nứt. Khoảng cách giữa các lệch mạng này trùng khớp với khoảng cách vân sọc quan sát trên bề mặt phá hủy, cho thấy bước phát triển của vết nứt được chi phối bởi sự sắp xếp nội tại của lệch mạng thay vì chiều dài vết nứt tổng thể. Một cơ chế chịu sự điều khiển của vi cấu trúc, bao gồm chu kỳ phát xạ lệch mạng, hóa bền biến dạng, tiến triển và dừng vết nứt, được đề xuất.
Article Details
This work is licensed under a Creative Commons Attribution-NonCommercial 4.0 International License.
References
Huynh, T. T., Shigeru, H., Kaneaki, T., & Hiroshi, N. (2021). Microscopic examination of striation spacing during ductile crack growth in Fe-3wt%Si single-crystalline thin plates in air and hydrogen. Materials Science and Engineering: A, 802, 140652.
https://doi.org/10.1016/j.msea.2020.140652
Huynh, T. T., Motomichi, K., Yoshimasa, T., Shigeru, H., Kaneaki, T., & Hiroshi, N. (2020). Plastic Deformation Sequence and Strain Gradient Characteristics of Hydrogen-Induced Delayed Crack Propagation in Single-Crystalline Fe–Si Alloy. Scripta Materialia, 178, 99–103. https://doi.org/10.1016/j.scriptamat.2019.11.012
Inês, S., Maria, Evgenii, M., Telmo, G. S., & Pedro, V. (2023). Review of Conventional and Advanced Non-Destructive Testing Techniques for Detection and Characterization of Small-Scale Defects. Progress in Materials Science, 138, 101155.
https://doi.org/10.1016/j.pmatsci.2023.101155
Kromm, A., Lausch, T., Schroepfer, D., Rhode, M., & Kannengiesser, T. (2020). Influence of Welding Stresses on Relief Cracking during Heat Treatment of a Creep-Resistant 13CrMoV Steel Part II: Mechanisms of Stress Relief Cracking during Post Weld Heat Treatment. Welding in the World, 64(5), 819–29.
https://doi.org/10.1007/s40194-020-00881-8
Kuhlmann-Wilsdorf, D. (1987a). Energy Minimization of Dislocations in Low‐energy Dislocation Structures. Physica Status Solidi (a), 104(1) , 121–44. https://doi.org/10.1002/pssa.2211040109
Kuhlmann-Wilsdorf, D. (1987b). LEDS: Properties and Effects of Low Energy Dislocation Structures. Materials Science and Engineering, 86, 53–66.
https://doi.org/10.1016/0025-5416(87)90442-3
Liu, X. Y., & McMahon, C. J. (2009). Quench Cracking in Steel as a Case of Hydrogen Embrittlement. Materials Science and Engineering: A, 499(1–2), 540–41. https://doi.org/10.1016/j.msea.2008.08.035
Moynihan, M., C., & Julian, M. A. (2014). “Utilization of Structural Steel in Buildings.” Proceedings of the Royal Society A: Mathematical, Physical and Engineering Sciences, 470(2168). https://doi.org/10.1098/rspa.2014.0170
Lii, M., Foecke, T., Chen, X., Zielinski, W., & Gerberich, W. W. (1989). The effect of low energy dislocation structures on crack growth onset in brittle crystals. Materials Science and Engineering: A, 113, 327–338. https://doi.org/10.1016/0921-5093(89)90321-3
Nanninga, N., A. Slifka, Levy, Y., & White, C. (2010). “A Review of Fatigue Crack Growth for Pipeline Steels Exposed to Hydrogen. Journal of Research of the National Institute of Standards and Technology, 115(6), 437. https://doi.org/10.6028/jres.115.030
Nes, E. (1997). Modelling of Work Hardening and Stress Saturation in FCC Metals. Progress in Materials Science, 41(3), 129–93. https://doi.org/10.1016/S0079-6425(97)00032-7
Pang, B., Jones, I. P., Yu, L. C, Millett, J. C. F., & Glenn, W. (2017). Electron Channelling Contrast Imaging of Dislocations in a Conventional SEM. Philosophical Magazine, 97(5), 346–59. https://doi.org/10.1080/14786435.2016.1262971
Picard, Y. N., Liu, M., Lammatao, J., Kamaladasa, R., & Graef, M. D. (2014). Theory of Dynamical Electron Channeling Contrast Images of Near-Surface Crystal Defects. Ultramicroscopy, 146, 71–78.
https://doi.org/10.1016/j.ultramic.2014.07.006
Pippan, R., & Hohenwarter, A. (2017). Fatigue Crack Closure: A Review of the Physical Phenomena. Fatigue & Fracture of Engineering Materials & Structures, 40(4), 471.
https://doi.org/10.1111/ffe.12578
Rice, R. J. (1987). Tensile Crack Tip Fields in Elastic-Ideally Plastic Crystals. Mechanics of Materials, 6(4), 317–35. https://doi.org/10.1016/0167-6636(87)90030-5
Ritchie, R. O., Gilbert, C. J., & McNaney, J. M. (2000). Mechanics and Mechanisms of Fatigue Damage and Crack Growth in Advanced Materials. International Journal of Solids and Structures, 37(1–2), 311–29. https://doi.org/10.1016/S0020-7683(99)00096-7
Shen, X., Xu, L., Jinxuan, G., Ying, L., Junyi, Q, & Zhenfei, L. (2023). Nondestructive Testing of Metal Cracks: Contemporary Methods and Emerging Challenges. Crystals, 14(1), 54. https://doi.org/10.3390/cryst14010054
Stewart, M. (2021). Materials Selection for Pressure Vessels. Surface Production Operations, 93–116.
https://doi.org/10.1016/B978-0-12-803722-5.00004-5
Vakili, M., Petr, K., Jan, K., & Zahra, G. (2024). Analysis, Assessment, and Mitigation of Stress Corrosion Cracking in Austenitic Stainless Steels in the Oil and Gas Sector: A Review. Surfaces 2024, 7(3), 589–642. https://doi.org/10.3390/surfaces7030040
Zaefferer, S., & Nahid, N. E. (2014). Theory and Application of Electron Channelling Contrast Imaging under Controlled Diffraction Conditions. Acta Materialia, 75, 20–50. https://doi.org/10.1016/j.actamat.2014.04.018
Zhang, J. L., Zaefferer, S., & Raabe, D. (2015). A Study on the Geometry of Dislocation Patterns in the Surrounding of Nanoindents in a TWIP Steel Using Electron Channeling Contrast Imaging and Discrete Dislocation Dynamics Simulations. Materials Science and Engineering: A, 636, 231–42.
https://doi.org/10.1016/j.msea.2015.03.078