PSI - Issue 13

Yoshiki Mikami et al. / Procedia Structural Integrity 13 (2018) 1804–1810 Author name / Structural Integrity Procedia 00 (2018) 000–000

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5. Conclusion In this study, the processes of multipass welding, specimen machining, notch introduction, residual stress modification (reverse bending, in this paper), precracking, and three-point bending was simulated. The residual stress distribution was validated by the measurement result, and it was incorporated into the simulation. Then, the three point bend CTOD test was simulated and the effect of the residual stress distribution on the crack-tip opening profile was investigated. The obtained results are summarised as follows:  The residual stress distribution at the notch root could be modified by the reverse bending technique.  The P – V g curve is affected by the residual stress distribution; however, the influence is relatively small compared to that on the crack-tip opening profile.  The crack-tip opening profile was strongly affected by the weld residual stress, and it is not visible by P – V g curves. It was demonstrated that the weld residual stress in thick steel welds has a significant effect on the CTOD test. The proposed method could be a useful approach to investigate the effect of the weld residual stress on fracture toughness evaluation. Fracture mechanics simulations of weldments could be performed by the proposed simulation procedure. Acknowledgements The authors wish to acknowledge the members of the Commission CTE of the Japanese Welding Engineering Society for their helpful discussions during the course of this study. References International Organization for Standardization, 2002, ISO 12135: Unified method of test for the determination of quasistatic fracture toughness. British Standards Institution, 1991, BS 7448 Part 1: Fracture mechanics toughness tests. Method for determining of K Ic , critical crack tip opening displacement (CTOD) and critical J values of metallic materials. The Japan Welding Engineering Society, 2016, WES 1108: Standard test method for crack-tip opening displacement (CTOD) fracture toughness measurement. International Organization for Standardization, 2018, ISO 15653: Metallic materials—Method of test for the determination of quasistatic fracture toughness of welds. Mikami, Y., Kawabata T., Tagawa, T., Kitano, H., Kiuchi, A., Kayamori, Y., Kanna, S., Sakurai, T., Imai, Y., Ohata, M., Mochizuki, M., Minami, M., Aihara, S., Hagihara, Y., 2017. Numerical simulation of residual stress modification by reverse bending of notched fracture toughness test specimens of multipass welds. Theoretical and Applied Fracture Mechanics 92, 214–222. American Petroleum Institute, 2005, Recommended Practice for Preproduction Qualification for Steel Plates for Offshore Structures, API Recommended Practice 2Z, Fourth Edition. Takahashi, E., Iwai, K., Satoh, K., 1979 A method of measuring triaxial residual stress in heavy section butt weldments. Transactions of the Japan Welding Society 10, 36–45.