PSI - Issue 28

V.V. Sudin et al. / Procedia Structural Integrity 28 (2020) 1637–1643 Sudin V.V./ Structural Integrity Procedia 00 (2019) 000–000

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5. Conclusions  During Sharpy tests of low-alloy steels and their welded joints, it is possible to obtain values of impact toughness, at which the specimen is considered successful by the level of energy spent on fracture, while the energy spent before the formation of a brittle crack has a value significantly lower than the required level of total energy of fracture.  The Probability of such results differs for a metal with different microstructures. For welds it is significantly higher than for steel 09G2S.  There Is a correlation between the displacement of tester pendulum to the formation of a brittle fracture during impact bending tests and the distance from the notch root to the facet area on the fracture surface of the specimen, which is close for specimens with different microstructures.  The early occurrence of a brittle fracture, accompanied by a large amount of energy spent on the final fracture of the specimen, can occur quite often in welded joints made by some methods, and may pose a danger to the structural integrity of welded metal structures.  Control of the early origin of a brittle crack is possible by measuring the distance from the notch root to the area of brittle facets in the fracture image using the shown correlation between the displacement of the tester pendulum to the formation of a cleavage fracture and the distance from the notch root to the area of brittle facets. It is not possible to replace the depth parameter of a ductile crack with percentage of shear fracture area. Acknowledgements The work was performed in the framework of the state task GZ №075-00947-20-00 and with help of gran UMNIK Cao, R., Li, J., Liu, D. S., Ma, J. Y., Chen, J. H. (2015). Micromechanism of decrease of impact toughness in coarse-grain heat-affected zone of HSLA steel with increasing welding heat input. Metallurgical and Materials Transactions A, 46(7), 2999-3014. Cao, R., Zhang, X. B., Wang, Z., Peng, Y., Du, W. S., Tian, Z. L., Chen, J. H. (2014). Investigation of microstructural features determining the toughness of 980 MPa bainitic weld metal. Metallurgical and Materials Transactions A, 45(2), 815-834. Chen, J., Cao, R. (2017). Micromechanism of cleavage fracture of weld metals. Acta Metall Sin, 53(11), 1427-1444. Easterling, K. (2013). Introduction to the physical metallurgy of welding. Elsevier. Fabry, A., Walle, E. V., Chaouadi, R., Wannijn, J. P., Werstrepen, A., Puzzolante, J. L., VandeVelde, J. (1993). RPV steel embrittlement: Damage modeling and micro-mechanics in an engineering perspective (No. NEA-CSNI-R--94-1). Gerard, R., Fabry, A., Van de Velde, J., Puzzolante, J. L., Verstrepen, A., Van Ransbeeck, T., Van Walle, E. (1996). In-service embrittlement of the pressure vessel welds at the Doel I and II nuclear power plants. In Effects of Radiation on Materials: 17th International Symposium. ASTM International. GOST (State Standard) R ISO 148-1-2013: Metals. Method for testing the impact strength at low, room and high temperature, Moscow: Standartinform, 2014. Hartbower, C. E., Orner, G. M. (1963). Metallurgical variables affecting fracture toughness in high-strength sheet alloys. Manlabs Inc Cambridge Mass. Kantor, M. M., Bozhenov, V. A. (2014). Scattering of values of impact toughness of low-alloy steel in the ductile-brittle transition temperature region. Inorganic Materials: Applied Research, 5(4), 293-302. Otani, M. (1957). Study of sensitivity of welded joints to cut at dynamic tests of double strike/J. Railway Engineering Research, 14(11), 503-529. Shtremel’, M.A., Razrushenie. Kniga 1. Razrushenien materialov (Fracture, Book 1: Fracture of Materials), 2014, Moscow: Mosk. Inst. Stali Splavov. Tanguy, B., Besson, J., Piques, R., Pineau, A. (2005). Ductile to brittle transition of an A508 steel characterized by Charpy impact test: Part I: Experimental results. Engineering fracture mechanics, 72(1), 49-72. №U-49202 References