PSI - Issue 13

Taketo Kaida et al. / Procedia Structural Integrity 13 (2018) 1076–1081 Taketo Kaida et al. / Structural Integrity Procedia 00 (2018) 000–000

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(1) In the crack propagation process, we performed the qualitative assessment of the plastic zone developments underneath the fracture surface. (2) Through the observation of the dislocation structures underneath the fracture surface, it was shown that ∆ K can be qualitatively estimated from the transformation of dislocation structures. (3) In the vein-to-labyrinth transformation process, we investigated the state of the dislocation wall tilting, as a function of the distance from the fracture surface. This indicates the possibility of estimating the stress distribution from the dislocation structures. Acknowledgements Authors SH, MK, and HN acknowledge the financial support by JSPS KAKENHI (JP16H06365). References Forsyth, P.J.E., Ryder, D.A., 1960. Fatigue fracture: Some results derived from the microscopic examination of crack surfaces. Aircraft Engineering and Aerospace Technology 32, 96-99. Habib, K., Koyama, M., Tsuchiyama, T., Noguchi, H., 2018. Visualization of dislocations through electron channeling contrast imaging at fatigue crack tip, interacting with pre-existing dislocations. Materials Research Letters 6, 61-66. Kaneko, T., Koyama, M., Fujisawa, T., Tsuzaki, K., 2016. Combined multi-scale analyses on strain/damage/microstructure in steel: Example of damage evolution associated with ε-martensitic transformation. ISIJ International 56, 2037-2046. Kimura, H., Akiniwa, Y., Tanaka, K., Tahara, Y., Hattori Y., Ishikawa, T., 2003. Effect of crystallographic orientation and microstructure on fatigue crack propagation behavior in ultrafine-grained steel (SUF steel). The Japan Society of Mechanical Engineers 1, 705, 117-118. Koyama, M., Akiyama, E., Tsuzaki, K., Raabe, D., 2013. Hydrogen-assisted fracture in a twinning-induced plasticity steel studied under in situ hydrogen charging by electron channeling contrast imaging. Acta Materialia 61, 4607-4618. Koyama, M., Yamanouchi, K., Wang, Q., Ri, S., Tanaka, Y., Hamano, Y., Yamasaki, S., Mitsuhara, M., Ohkubo, M., Noguchi, H., Tsuzaki, K., 2017. Multiscale in situ deformation experiments: A sequential process from strain localization to fracture in a laminated Ti-6Al-4V alloy. Materials Characterization 128, 217-225. Murakami, Y., 1987. Stress Intensity Factors Handbook. Pergamon press 1, 9-10. Murakami, Y. Shimizu, M.., 1988. Effects of nonmetallic inclusions, small defects and small cracks on fatigue strength of metals. The Japan Society of Mechanical Engineers 54 499, 413-425. Nishikawa, H.-a., Oda, Y., Takahashi, Y., Noguchi, H., 2011. Microscopic observation of the brittle-striation formation mechanism in low carbon steel fatigued in hydrogen gas (TEM and EBSD observation corresponding to fractography). Journal of Solid Mechanics and Materials Engineering 5, 179-190. Onishi, Y., Koyama, M., Sasaki, D., Noguchi, H., 2016. Characteristic fatigue crack growth behavior of low carbon steel under low-pressure hydrogen gas atmosphere in an ultra-low frequency. ISIJ International 56, 865-870. Rieux, P., Driver, J., Rieu, J, 1978. Fatigue crack propagation in austenitic and ferritic stainless steel single crystals. Acta Materials 27, 145-153. Suzuki, T., Uno, T., Oyanagi, T., Hayashi, I., 1987. Crystallographic orientation dependence of fatigue crack propagation in Fe-3%Si (characteristics of crack propagation at an early stage under K Ⅰ + K Ⅱ mixed mode loading). The Japan Society of Mechanical Engineers 53, 486, 230-235. Zaefferer, S., Elhami, N.-N., 2014. Theory and application of electron channelling contrast imaging under controlled diffraction conditions. Acta Materialia 75, 20-50.