PSI - Issue 25

4

Francesco Leoni / Structural Integrity Procedia 00 (2019) 000–000

Francesco Leoni et al. / Procedia Structural Integrity 25 (2020) 348–354

351

Figure 3: A: Measured strain to fracture at different testing temperatures. B: Average values for the UTS at different testing temperatures.

The true stress-true strain curves at each temperature can then be calculated using input data from Figure 2 and the appropriate conversion formulae provided by Dieter (1988). The results are presented graphically in Figure 4.

Figure 4: Calculated true stress-true strain curves for the 1.4 mm diameter AA6082 filler wire at different temperature.

0  varies with accumulated plastic strain p  at different

These curves, which show how the plastic flow stress temperatures, can be described by Ludwik’s law:

n

0 p k    (1) where n and k are the strain hardening coefficient and the strength coefficient, respectively. Table 2 summarizes the values of n and k being obtained following the fitting of Equation (1) to the experimental data in Figure 4.

Table 2: Values of n and k being obtained following the fitting of Equation (1) to the experimental data in Figure 4.

T = 25 °C

T = 100 °C

T = 200 °C

T = 350 °C

T = 500 °C

422

435

474 0.20

110 0.32

74

k n

0.027

0.076

0.41