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. 2. Chronogram of deformation front propagation at the stage of steady-state creep for the stress  c = 57 MPa.

It is seen from Fig. 2 that steady-state creep in aluminum corresponds to a stationary distribution of plastic deformation fronts, which is characteristic of localized plasticity zones observed earlier at the stages of parabolic work hardening in metals and alloys during tension (Barannikova et al. (2004)). Based on the distributions of local elongations  xx along the tensile axis X (Fig. 3), we determined the spatial period of localization  as the distance between the peak values of  xx(x) . The average value of the spatial period was specified by summing up the values of local elongations throughout the entire stage of steady-state creep for each of the tested specimens. For example, at a stress of 51 MPa in the creep mode the plastic strain localization period  = 4.5±1 mm, which is consistent with the data obtained earlier at the stage of parabolic work hardening during tension of metals and alloys (e.g. Barannikova et al. (2004), Barannikova et al. (2009), Nadezhkin and Barannikova (2021)).

Fig. 3. Distribution of local elongations  xx along the tensile axis at the stage of steady-state creep for the stress  c = 57 MPa.

It was found that both the spatial period of plastic strain localization and the creep rate change with the level of applied creep stresses (Fig. 4).