Issue 43

M.P. Tretyakov et alii, Frattura ed Integrità Strutturale, 43 (2018) 146-154; DOI: 10.3221/IGF-ESIS.43.11 152 a b c d Figure 8 : Distribution of longitudinal strain ε yy along the length of test part of specimens at regular time intervals: initial specimens deformed to level 3 ( a and b ), specimen turned along entire length ( c ) , specimen turned in necking area ( d ) . As you can see in the Fig. 8 ( a and b ), during tension of the initial specimens the longitudinal strain distribution is homogeneous along the length up to the 4-th profile, starting from the 5-th profile, strain localization and further neck formation are observed. Because of the analysis of the strain distribution in the tensile tests of specimens prepared according to the scheme 1 (Fig. 8, c ), it was noted that the inhomogeneity of the longitudinal strain distribution is already observed from the 2-nd profile. The minimal longitudinal strain registered in the test part is corresponded to the necking zone on the initial specimen. Thus, in the case of tension the specimens turned along the entire length of test part, already at the initial stage of the test, strain is localized in the peripheral area of the test part of the initial specimen. The maximum longitudinal strain in the neck are comparable with the values of the maximum strain registered during the tension of the initial specimens, which indicates the presence of deformation reserves of the material in the peripheral area. At the same time, a lower level of maximum longitudinal strain in the neck of the specimens prepared according to scheme 2 (Fig. 8, d ) demonstrates a decrease in the deformation reserves of the material in the neck zone of the initial specimen. C ONCLUSION uring the research work, an experimental study of the regularities of mechanical behavior of structural steel 40Cr under postcritical deformation of solid cylindrical specimens at tension was conducted. Particular attention is paid to the registration and interpretation of experimental data in the context of the formation of the strain localization as a necking effect. The results of the "specimen from specimen" test scheme are given. With preliminary stretching of the initial specimens, different levels of postcritical deformation are implemented. From the obtained specimens, the specimens D