PSI - Issue 64

Mao Ye et al. / Procedia Structural Integrity 64 (2024) 1824–1831 Author name / Structural Integrity Procedia 00 (2019) 000 – 000

1828

5

800

4% 6% 8% 10% 12% 16%

E 0

600

400

Stress plateau

Stress (MPa)

200

0 2 4 6 8 1012141618 0

Strain (%)

(a)

(b)

Fig. 3. (a) Stress-strain behavior of tensile specimen T-1; (b) Stress-strain behavior of prestraining specimens (No.1, 4, 5, 9, 12, and 13).

Table 2. Test results of prestraining, activation and re-activation.

Test type

Specimen No.

Prestrain level ε pre (%)

Elastic modulus E 0 (GPa)

Maximum tension stress σ max (MPa)

Residual strain ε res (%)

Activation temperature T act (℃) a

Recovery stress σ recov (MPa)

Prestraining & Activation

1 2 3 4 5 6 7

4

68.2 68.3 69.0 68.4 67.1 66.7 62.7 65.5 62.8 64.5 67.4 67.5 65.1 71.5 64.7 69.1 63.2 65.3

587.3 588.0 586.9 612.5 630.5 639.5 603.5 616.8 660.5 678.3 693.0 694.7 778.3 778.2 786.8 703.6 655.4 666.8

2.31 2.26 2.36 3.85 5.65 5.61 5.75 5.59 7.44 7.42 7.22 9.03

120 180 240 180 120 180 240 300 180 180 180 180 120 180 240

295.9 344.9 343.9 375.3 341.0 448.6 438.4 410.9 409.2 428.2 408.0 375.3 273.2 330.8 380.4

6 8

8 b 9 c

10

10 d 11 e

12 13 14 15 16 17 18

12 16

12.63 12.65 12.64

Prestraining & Activation & Re activation

10

7.43 7.43 7.43

120→180 180→240 240→240

355.2 → 418.0 414.2 → 443.2 440.9 → 445.0

Average 66.4 a For most activation tests, the average heating rate of each specimen was between 12~24 ℃ per minute.

b Recovery stress monitored for 12 hours after activation. c Slow heating rate, about 9 ℃ per minute on average. d Rapid heating rate, about 41 ℃ per minute on average. e Initial preload of 50 MPa was applied, while 20 MPa for all the other specimens.