PSI - Issue 41

Abdelmoumene Guedri et al. / Procedia Structural Integrity 41 (2022) 564–575 Abdelmoumene Guedri et al. / Structural Integrity Procedia 00 (2022) 000–000

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Fig. 8. Longitudinal section of a sample deformed by traction at 950°C.

Fig. 9. Longitudinal section of a sample deformed by pulling at 950°C.

4. Flow stress prediction using ANN approach 4.1. Stress strain curves

The stress-strain curves were obtained from the force-elongation curves, and are plotted after the elimination of the elastic part. The latter have a general appearance represented by a rapid rise to the increasing parabolic pace where the peaks do not seem predominant followed by a rapid decrease due to the phenomenon of appearance of necking. The tensile curves obtained Figure 10 shows a fairly wide upward progression followed by a more or less rapid descent of the stress. This typical appearance suggests the presence of a softening mechanism which increases when the test temperature increases (T = 800°C). This causes a decrease in tensile strength whose peak stress  max goes from over 140 MPa at 800°C to less than 60 MPa at 950°C. It also causes a slight decrease in the rate of deformation