PSI - Issue 50

Mikhail Nadezhkin et al. / Procedia Structural Integrity 50 (2023) 206–211 Author name / Structural Integrity Procedia 00 (2019) 000 – 000

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Fig. 4. Dependence of localization period  (1) and creep rate έ (2) versus stress  c at the stage of steady-state creep.

Figure 4 shows that the dependences of localization period  (1) and creep rate έ (2) on stress  c are linear, with a high value of the correlation coefficient. The proportionality of the localization period and the creep rate apparently indicates the identity of the micromechanisms governing both of these phenomena. As is known from Wilshire and Burt (2003), creep in metals is governed by thermally activated dislocation glide. Therefore, macroscopic plastic strain localization is also characteristic of creep deformation. 4. Summary In this work, the digital image correlation method was used to show that the distributions of local elongations of the plastic distortion tensor over a specimen of commercially pure aluminum are periodic and stationary at the stages of steady-state creep for all stress values used. They are similar to the patterns observed at the stages of parabolic work hardening under high-rate loading. Plastic deformation at each time point is localized in certain equidistant regions of the specimen. Adjacent zones remain practically undeformed in this case. The spatial period in the system of localization zones remains constant during the entire stage of steady-state creep. It was found that the stress dependences of the creep rate and the spatial period of plastic strain localization in steady-state creep are linear. Acknowledgements This work was supported by the Russian Science Foundation (grant no. 21-19-00075) . References Barannikova, S.A., Danilov, V.I., Zuev, L.B., 2004. Plastic strain localization in Fe-3%Si single crystals and polycrystals under tension. Technical Physics 49, 1296 – 1300. Barannikova, S.A., Nadezhkin, M.V., Zuev, L.B., 2009. On the localization of plastic flow under compression of NaCl and KCl crystals. Physics of the Solid State 51, 1142 – 1148. Chirkov, A., Pazhin, A., Eremin, M., 2021 Numerical modeling of kinetic regularities of yield plateau and linear work hardening stages during tension of mild steel samples. Procedia Structural Integrity 31, 80-85. Hall, J.S., Fromme, P., Michaels, J.E., 2014. Guided wave damage characterization via minimum variance imaging with a distributed array of ultrasonic sensors. Journal of Nondestructive Evaluation 33(3), 299 – 308. Kocks, U.F., 1976. Laws for work-hardening and low-temperature creep. Journal of Engineering Materials and Technology, Transactions of the ASME 98(1), 76 – 85. Mello, A.W., Nicolas, A., Lebensoh, R.A., Sangid, M.D., 2016. Effect of microstructure on strain localization in a 7050 aluminum alloy: Comparison of experiments and modeling for various textures. Materials Science and Engineering A 661, 187 – 197. Nadezhkin, M.V., Barannikova, S.A., 2021. Loading Velocity and Kinetics of Localized Bands of Nickel Plastic Deformation. Russian Physics Journal 64, 1422 – 1426.