PSI - Issue 14

Pankaj Kumar et al. / Procedia Structural Integrity 14 (2019) 96–103 Author name / Structural Integrity Procedia 00 (2018) 000 – 000

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4. Results and discussion

4.1. Experimental results

Fig. 2. Experimental and simulated stress strain curve for (a) cryorolled; (b) annealed cryorolled AA 5754 alloy

Experimental and simulated stress strain curve for CR and ACR alloys are shown in Fig. 2. Table 1 signifies that the tensile strength and ductility is enhanced for ACR alloys due to PAHT process. This may be due the annealing of CR alloys which provides enough time and temperature to recover the residual stress arises during low temperature rolling.

Table 1. Tensile test results for cryorolled and annealed cryorolled alloys. Material properties

Yield strength ( MPa ) Tensile strength ( MPa ) Elongation ( % )

Cryorolled

250

368 446

7.60

Annealed cryorolled 280

15.66

The strain controlled LCF test results are presented in Fig. 3 which indicates that fatigue life is enhanced for annealed CR alloys at corresponding strain amplitudes. LCF tests reveal that cryorolled alloys show mild hardening in the initial cycles followed by noticeable cyclic softening at all strain amplitudes. In contrast, only cyclic hardening behavior is depicted by ACR specimens at each of the tested strain amplitudes.

Fig. 3. Fatigue life at different strain amplitudes of (a) cryorolled; (b) annealed cryorolled AA 5754 alloy