PSI - Issue 65

A.S. Smirnov et al. / Procedia Structural Integrity 65 (2024) 255–262 A.S. Smirnov, A.V. Konovalov,V.S. Kanakin and I.A. Spirina/ Structural Integrity Procedia 00 (2024) 000–000

260

6

(a)

(b)

VI

6

1.4

1.2

5

1.0

4

V

0.8

3

0.6

Strain rate (1/s)

Strain rate (1/s)

2

0.4

IV

1

0.2

0

0.0

0.00

0.05

0.10

0.15

0.20

0

1

2

3

4

5

6

Time (s)

Time (s)

(c)

(d)

500 С

500 С

VI

80

90

60

IV

60

40

V

Flow stress (MPa)

Flow stress (MPa)

30

20

0

0

0

1

2

3

4

5

6

0.00

0.05

0.10

0.15

0.20

Time (s)

Time (s)

Fig. 3. Forms of loading IV–VII (a, b); experimental (blue) and model-simulated (orange) curves showing the time dependences of flow stress for the V95\3% TiC MMC deformed at 500 � (c, d).

The table shows the coefficients of model (1) for the temperature range from 300 to 500 °C and the strain rates range between 0.1 and 5 s 1 .

Table 1. Coefficients of the flow stress model

a 0

a 1

a 2

a 3

a 4

a 5

a 6

a 7 300 ℃ 400 ℃ 500 ℃

a 8

a 9

a 1 0

a 11

a 12

a 13

a 14

42

276337

0.03

3.65 0.8

2.75

0.0244

0.0149

23

24.9

0.57

0.003

3.95

0.002

0.002

27

187220

0.02

9.13 0.6

1.31

0.0295

0.0594

17

37.3

0.47

0.006

3.97

0.022

0.001

9

191169

0.02

0.02 0.2

14.56

0.0571

2.0948

17

10.4

0.48

9.432

3.75

0.001

0.015

The flow stress curves obtained by model (1) with the coefficients from the table are shown by orange in Figs. 2 and 3. The average relative deviation of the experimental curves from the calculated ones for the entire range of temperatures and strain rates did not exceed 6%, and this corresponds to acceptable engineering accuracy. Figure 4 shows the strain dependences of flow stress for constant strain rates, calculated by model (1) with the coefficients from the table. As can be seen from this figure, at strain rates above 0.1 s 1 and temperatures of 300 and 500 °C, the flow stress curves have a maximum value (peak), after which the flow stress decreases with increasing strain. This