PSI - Issue 33

M.P. Tretyakov et al. / Procedia Structural Integrity 33 (2021) 1089–1094 Author name / Structural Integrity Procedia 00 (2019) 000–000

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Fig. 5 and Fig. 6 show tensile diagrams obtained with a loading system stiffness of 18 MN/m and 5 MN/m, respectively. Fig. 5 shows that a decrease in the loading rigidity to 18 MN/m led to a change in the form of the deformation diagram. The curve is characterized by the presence of a large number of closely spaced teeth associated with intermittent deformation processes. Fig. 5 (b) shows an enlarged fragment of the strain hardening section. A further decrease in the rigidity of the loading system to 5 MN/m led to a change in the type of teeth and an increase in their magnitude in stress. Thus, as a result of tensile tests, deformation diagrams were obtained for Al-Mg alloy samples tested at different values of the rigidity of the loading system: 120 MN/m (nominal value), 50 MN/m, 18 MN/m, and 5 MN/m. All diagrams show discontinuous plastic deformation (Portevin-Le Chatelier effect). A decrease in the rigidity of loading with respect to the working part of the sample led to a change in the form of deformation diagrams, reflecting the course of intermittent flow processes, and an increase in the magnitude of the stress drop at each tooth of the diagram. The indicated effects of inhomogeneous plastic deformation are observed both at the stage of strain hardening and at the stage of postcritical deformation. A change in the rigidity of the loading system in the considered range did not lead to a change in the level of stresses, which corresponded to the onset of the onset of processes of inhomogeneous intermittent plastic deformation. For all tests, this level was in the stress range from 290 MPa to 310 MPa. Acknowledgements The reported study was carried out in Perm National Research Polytechnic University and was funded by RFBR, project number 20-38-70166, and with financial support of grant of President of Russian Federation for government support of young Russian scientists (Grant № МК-885.2020.1) References Yilmaz A., 2011. The Portevin-Le Chatelier effect: a review of experimental findings, Sci. Technol. Adv. Mater 12, 1‒16. Aguirre F., Kyriakides S., Yun H.D., 2004. Bending of steel tubes with Lüders bands, International Journal of Plasticity 20, 1199–1225. Tretyakova T.V., Wildemann V.E., 2016. Spatial-time inhomogeneity of the processes of inelastic deformation of metals, Moscow, Fizmatlit. pp. 120. Tretyakova T.V., Wildemann V.E., 2019. Experimental study of the influence of strain-stress state on the jerky flow in metals and alloys. Procedia Structural Integrity 17, 906-913. Vildeman, V.E., Sokolkin, Yu.V., Tashkinov, А.А., 1997. Mechanics of inelastic deformation and fracture of composite materials, Moscow, Nauka. pp. 288. Tretyakov, M.P., Wildemann, V.E., Lomakin, E.V., 2016. Failure of materials on the postcritical deformation stage at different types of the stress strain state, Procedia Structural Integrity 2, 3721-3726. Tretyakov, M.P., Tretyakova, T.V., Wildemann, V.E., 2018. Regularities of mechanical behavior of steel 40Cr during the postcritical deformation of specimens in condition of necking effect at tension. Frattura ed Integrità Strutturale 43, 145-153. Videlman V.E., Tretyakov M.P., 2013. Analysis of the effect of loading system rigidity on postcritical material strain, Journal of Machinery Manufacture and Reliability 42 (3), 219-226.