PSI - Issue 33

Tatyana Tretyakova et al. / Procedia Structural Integrity 33 (2021) 1082–1088 Author name / Structural Integrity Procedia 00 (2019) 000–000

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Table 2. The test program for aluminum-magnesium alloy samples.

Test

Loading rate, mm/min Optional parameter

Tension test with a constant kinematic loading 2.4 Tension test with a constant kinematic loading 0.24

- -

Strain level of 1.8 % Strain level of 2.4 % Strain level of 1.8 %

Tension test with short stops

2.4

Non-monotonic tension test

2.4 →0.24

Loading rate change at strain level of 10 %

1

y

2

x

Fig. 2. Set of loading and diagnostic equipment: an ‘Instron 8850’ biaxial servo hydraulic testing machine (1), a Vic-3D digital-image-correlation measurement system (2) (left) and the local strain rate fields estimated by DIC-system (right) 3. Results and discussions 3.1. The Portevin-Le Chatelier effect depending on the loading rate during uniaxial tension test Since in this work the study of the effect of stops and non-monotonic loading will be carried out at loading rates of 0.24 and 2.4 mm per minute, it is necessary to obtain information about the configuration of the deformation curves at the specified values of the tensile rate. As a result of tests with a tensile rate of 2.4 mm/min, ‘stress-elongation’ diagrams were obtained, characterized by the presence of intermittent plastic deformation of type A (single large teeth), see Fig. 3. When tested at a loading rate of 0.24 mm/min, σ-u diagrams were obtained demonstrating intermittent flow processes of another type (type C). The corresponding deformation curves are shown in Fig. 4.